Magnetic coupler for well drilling

Abstract

The magnetic coupler comprises a body with an inner cavity, a permanent magnet capable of generating a magnetic field is arranged in the inner cavity, the permanent magnet is further sleeved with a conductor, and the conductor can rotate in the magnetic field under the action of external force. Eddy current is generated in the conductor, and then an anti-induced magnetic field is generated, so that the permanent magnet can be driven by the anti-induced magnetic field to rotate. The magnetic coupler for well drilling can reduce the temperature of the conductor, so that the reliability of the magnetic coupler is improved, and the service life of the magnetic coupler is prolonged.

Description

Technical Field

[0001] The invention relates to a magnetic coupler for drilling. Background Art

[0002] A magnetic coupler is a device that transmits torque from the upper power structure to the load through the air gap between the conductor and the permanent magnet, and can achieve transmission of power to the load device shaft without mechanical connection. The working principle of the magnetic coupler is to form a magnetic field around the conductor through a permanent magnet. When the permanent magnet and the conductor produce relative motion, the conductor can quickly cut the magnetic lines of force, thereby generating eddy currents in the conductor. Subsequently, the eddy currents will generate an anti-inductive magnetic field, which interacts with the magnetic field generated by the permanent magnet, pulling the permanent magnet and the conductor to move relative to each other, thereby achieving torque transmission between the two.

[0003] Magnetic couplers are widely used in petroleum engineering fields such as drilling because of their advantages such as flexible start-up, simple structure, overload protection, strong environmental adaptability and long service life.

[0004] However, in actual use, the conductor will heat up under the action of eddy current, causing the temperature of the conductor to continue to rise during long-term use. When the temperature of the conductor rises to a certain threshold, it will cause damage to the conductor, which will seriously affect the normal use of the conductor and reduce the reliability and service life of the magnetic coupler. Summary of the invention

[0005] In view of the above technical problems, the present invention aims to provide a magnetic coupler for drilling. The magnetic coupler for drilling of the present invention can reduce the temperature of the conductor, thereby improving the reliability and service life of the magnetic coupler.

[0006] According to the present invention, there is provided a magnetic coupler for drilling, comprising a main body having an inner cavity, wherein a permanent magnet capable of generating a magnetic field is arranged in the inner cavity, and a conductor is also sleeved on the outside of the permanent magnet, wherein the conductor can rotate in the magnetic field under the action of an external force, thereby generating eddy currents in the conductor and then generating an anti-inductive magnetic field, so that the permanent magnet can rotate under the drive of the anti-inductive magnetic field.

[0007] In a preferred embodiment, a gap is provided between the conductor and the permanent magnet, and a liquid inlet and a liquid outlet connecting the gap and the outside of the body are respectively provided on the body at the upper and lower ends of the gap, so that downhole fluid can flow through the body from between the conductor and the permanent magnet.

[0008] In a preferred embodiment, an isolating tube is further provided in the gap, and the isolating tube is configured to separate the gap into an outer annulus close to the conductor and an inner annulus close to the permanent magnet, and the liquid inlet and the liquid outlet are configured to be connected to the outer annulus.

[0009] In a preferred embodiment, a first friction-reducing and drag-reducing element connecting the conductor and the isolation cylinder is further provided in the outer annulus.

[0010] In a preferred embodiment, slots are respectively provided on the outer walls of the upper and lower ends of the isolation cylinder, and the first friction and resistance reducing element is fixedly disposed in the slots.

[0011] In a preferred embodiment, the first friction and drag reducing element is configured as an angular contact ball bearing.

[0012] In a preferred embodiment, an upper joint capable of connecting a drill rod is further provided on the main body, and the permanent magnet is configured to be fixedly connected to the inner wall of the main body.

[0013] In a preferred embodiment, a core shaft is also connected to the permanent magnet, the upper end of the core shaft is fixedly extended into the permanent magnet so that it can rotate synchronously under the drive of the permanent magnet, and the lower end of the core shaft is arranged to extend out of the body.

[0014] A lower joint capable of connecting a load is also arranged at the lower end of the core shaft.

[0015] In a preferred embodiment, a seal is further provided between the core shaft and the body.

[0016] In a preferred embodiment, the isolation cylinder is made of a non-magnetic alloy material, and the conductor is made of a metal material. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be described below with reference to the accompanying drawings.

[0018] Figure 1 A schematic diagram of a magnetic coupler for drilling according to one embodiment of the present invention is shown.

[0019] In the present application, all drawings are schematic drawings, which are only used to illustrate the principles of the present invention, and are not necessarily drawn according to actual sizes and proportions. DETAILED DESCRIPTION

[0020] The present invention is described below by means of the accompanying drawings. In the following, the "upper end" or similar terms refer to the end close to the wellhead, and the "lower end" or similar terms refer to the end away from the wellhead.

[0021] Figure 1 FIG. 1 shows a schematic diagram of a magnetic coupling 100 for drilling according to an embodiment of the present invention. Figure 1 As shown, the magnetic coupler 100 for drilling comprises a body 10. The body 10 can be set to be cylindrical, for example. An inner cavity 20 is set in the body 10, and a permanent magnet 30 capable of generating a magnetic field is set in the inner cavity 20.

[0022] The permanent magnet 30 is configured to be able to rotate in the inner cavity 20 under the action of an external force. At the same time, a conductor 40 is also provided in the inner cavity 20 outside the permanent magnet 30. The conductor 40 is configured to be sleeved on the outside of the permanent magnet 30 and can rotate relative to the permanent magnet 30 under the action of an external force.

[0023] In the present invention, since the conductor 40 is sleeved on the outside of the permanent magnet 30, during the rotation of the conductor 40, it will rotate in the magnetic field generated by the permanent magnet 30, so that it can cut the magnetic flux lines. In the process of cutting the magnetic flux lines, eddy currents will be generated inside the conductor 40, thereby generating an anti-inductive magnetic field. After the anti-inductive magnetic field is generated, as the conductor 40 continues to rotate, the permanent magnet 30 located inside the conductor 40 will also rotate driven by the anti-inductive magnetic field.

[0024] Therefore, the operator can connect the active member (not shown) and the driven member (not shown) to the conductor 40 and the permanent magnet 30 respectively, drive the conductor 40 to rotate through the active member, and then drive the permanent magnet 30 to rotate, and then drive the driven member to rotate through the permanent magnet 30, thereby realizing the transmission connection between the active member and the driven member.

[0025] It should be noted that the generation principle of the eddy current and the anti-inductive magnetic field is well known to those skilled in the art, and a detailed introduction thereof is omitted here.

[0026] As the eddy current continues to be generated, the temperature of the conductor 40 will gradually increase. As the temperature of the conductor 40 continues to increase, the conductor 40 itself will be damaged, thereby increasing the risk of failure of the magnetic coupler 100.

[0027] Therefore, if Figure 1 As shown, an annular gap 50 is further provided between the conductor 40 and the permanent magnet 30 in the radial direction. The gap 50 is arranged along the axial direction of the body 10. At the same time, a liquid inlet 52 and a liquid outlet 54 are respectively provided on the body 10 at the upper and lower ends of the gap 50. The gap 50 can be connected to the underground space outside the body 10 through the liquid inlet 52 and the liquid outlet 54.

[0028] Through this arrangement, during the operation of the magnetic coupler 100, downhole fluid such as drilling fluid or mud in the oil well can flow into the body 10 from the fluid inlet 52, and then flow out through the gap 50 and the fluid outlet 54 in sequence. Thus, the downhole fluid can flow through the body 10 between the conductor 40 and the permanent magnet 30.

[0029] As the temperature of the conductor 40 continues to increase, the temperature of the conductor 40 will be much higher than the temperature of the downhole fluid such as drilling fluid or mud. Therefore, when the downhole fluid flows through the gap 50, it will contact the conductor 40, thereby continuously reducing the temperature of the conductor 40.

[0030] Therefore, through the cooling effect of the downhole fluid, the temperature of the conductor 40 will always be in a range close to that of the downhole fluid, thereby reducing the risk of high-temperature failure of the conductor 40 and further improving the reliability of the magnetic coupler 100.

[0031] Furthermore, an isolating cylinder 55 is further disposed in the gap 50 . The isolating cylinder 55 can be, for example, configured to be cylindrical, so as to be sleeved on the outer side of the permanent magnet 30 .

[0032] It is easy to understand that when the isolation tube 55 is located in the gap 50, it can separate the gap 50 into an outer annulus 56 close to the conductor 40 and an inner annulus 58 close to the permanent magnet 30. At the same time, the liquid inlet 52 and the liquid outlet 54 are arranged to communicate with the outer annulus 56.

[0033] Therefore, when the downhole fluid flows into the fluid inlet 52, it can only flow through the gap 50 from the outer annulus 56. In this way, the downhole fluid can be prevented from contacting the permanent magnet 30 through the isolation tube 55, thereby protecting the permanent magnet 30 and preventing the permanent magnet 30 from being corroded and damaged by the downhole fluid.

[0034] In the present invention, the conductor 40 is configured to be made of a metal material, and the metal material may be, for example, pure copper, to ensure that the conductor 40 has good electrical conductivity. At the same time, the isolation tube 55 is configured to be made of a non-magnetic alloy. The non-magnetic alloy may be, for example, tungsten carbide. Such a non-magnetic alloy will not shield the magnetic field, thereby preventing the isolation tube 55 from hindering the generation of eddy currents and anti-inductive magnetic fields, thereby ensuring the normal generation of eddy currents and anti-inductive magnetic fields.

[0035] In a preferred embodiment, a first friction-reducing and drag-reducing element 60 connecting the conductor 40 and the isolation tube 55 is further provided in the outer annulus 56. The first friction-reducing and drag-reducing element 60 is preferably provided in plurality, and the plurality of first friction-reducing and drag-reducing elements 60 are provided to be arranged axially on the outer walls at the upper and lower ends of the isolation tube 55. The first friction-reducing and drag-reducing element 60 can reduce the friction resistance between the conductor 40 and the isolation tube 55 when the conductor 40 rotates relative to the isolation tube 55, thereby reducing the rotation resistance of the conductor 40.

[0036] In the present invention, the first friction and drag reducing element 60 is preferably configured as an angular contact ball bearing. Such a bearing can bear radial load and axial load at the same time, and can work at a relatively high speed, and can be well applied to downhole drilling operations. At the same time, such a bearing will not close the outer annulus 56, and thus will not cause serious interference to the flow of downhole fluid.

[0037] In an embodiment not shown, a clamping groove is respectively provided on the outer wall of the upper and lower ends of the isolation cylinder 55, and the first friction and drag reducing element 60 is fixedly arranged in the clamping groove. The limiting effect of the clamping groove can prevent the first friction and drag reducing element 60 from moving along the axial direction of the isolation cylinder 55 during the rotation process, thereby improving the connection stability of the first friction and drag reducing element 60.

[0038] like Figure 1 As shown, an upper joint 11 is also provided at the upper end of the body 10. The body 10 can be connected to a downhole drill string (not shown) through the upper joint 11, so that the outer wall of the body 10 can be directly driven to rotate through the drill string. At the same time, the conductor 40 is configured to be fixedly connected to the inner wall of the body 10. The connection method can be, for example, welding, so that the rotation of the body 10 can directly drive the conductor 40 to rotate.

[0039] Through this arrangement, the conductor 40 can be directly driven by the downhole drill string to rotate synchronously, thereby minimizing the use of transmission parts and simplifying the structure of the magnetic coupler 100 as much as possible.

[0040] like Figure 1 As shown, a core shaft 35 is also connected to the permanent magnet 30. The core shaft 35 can be configured as a cylindrical shape, for example. The upper end of the core shaft 35 extends into the interior of the permanent magnet 30 so as to form a fixed connection with the permanent magnet 30. As a result, the core shaft 35 can be driven by the permanent magnet 30 to rotate synchronously.

[0041] Meanwhile, the lower end of the mandrel 35 is arranged to extend out of the body 10. In addition, a lower joint 36 is arranged at the lower end of the mandrel 35, so that the mandrel 35 can be connected to a load (not shown) such as a downhole drill bit through the lower joint 36, so that the load can rotate under the drive of the mandrel 35.

[0042] Through this arrangement, the load can be connected to the permanent magnet 30 through the core shaft 35. It is easy to understand that through this arrangement, the permanent magnet 30 can be prevented from extending outside the body 10 while achieving load connection, so that the lower end of the permanent magnet 30 can be prevented from contacting the downhole fluid, thereby further protecting the permanent magnet 30 and reducing the risk of corrosion damage to the permanent magnet 30.

[0043] like Figure 1 As shown, in one embodiment, a second friction-reducing and drag-reducing element 61 is provided between the lower joint 36 and the isolation cylinder 55. The second friction-reducing and drag-reducing element 61 is preferably provided in plurality, and the plurality of second friction-reducing and drag-reducing elements 61 are provided to be arranged axially on the inner wall of the lower end of the isolation cylinder 55. The provision of the second friction-reducing and drag-reducing element 61 can reduce the friction resistance between the lower joint 36 and the isolation cylinder 55 when the lower joint 36 rotates relative to the isolation cylinder 55, which is beneficial to the smooth operation of the magnetic coupling 100 used for drilling.

[0044] Preferably, in the present invention, the second friction and drag reducing element 61 is configured as an angular contact ball bearing, which can bear radial load and axial load at the same time and can work at a higher speed, and can be well applied to downhole drilling operations.

[0045] In one embodiment of the present invention, a slot is provided inside the isolating cylinder 55, and the second friction and drag reducing element 61 is provided in the slot. The limiting effect of the slot can prevent the second friction and drag reducing element 61 from axially moving along the isolating cylinder 55 during the rotation process, thereby improving the connection stability of the second friction and drag reducing element 61.

[0046] In addition, a seal 38 is provided between the core shaft 35 and the body 10. The seal 38 may be, for example, a sealing ring. The seal 38 can enhance the sealing performance of the body 10, thereby preventing downhole liquid from entering the body 10 through the connection portion, thereby corroding the permanent magnet in the body 10.

[0047] The working process of the magnetic coupler 100 for drilling according to the present invention is briefly described below.

[0048] The magnetic coupling device 100 for drilling of the present invention is used for drilling operations. During the drilling process, the operator can connect the magnetic coupling device 100 between the downhole drill string and the drill bit, so that the downhole drill string and the drill bit are connected to the upper joint 11 and the lower joint 36 respectively.

[0049] When the downhole drill string rotates, the body 10 connected to the downhole drill string will rotate synchronously, thereby driving the conductor 40 to rotate. As the conductor 40 rotates, it cuts the magnetic flux lines to generate eddy currents and anti-inductive magnetic fields. Subsequently, under the action of the anti-inductive magnetic field, the permanent magnet 30 will also rotate, thereby driving the drill bit to rotate, thereby achieving transmission.

[0050] In this process, downhole fluid such as drilling fluid can enter the gap 50 through the fluid inlet 52 and then be discharged from the fluid outlet 54. As the downhole fluid flows in the gap 50, it can reduce the temperature of the conductor 40, thereby protecting the conductor 40 and reducing the risk of damage to the conductor 40.

[0051] 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 magnetic coupler for drilling, comprising: A body (10) having an inner cavity (20), wherein a permanent magnet (30) capable of generating a magnetic field is arranged in the inner cavity, and a conductor (40) is also sleeved on the outside of the permanent magnet, wherein the conductor can rotate in the magnetic field under the action of an external force, thereby generating an eddy current in the conductor and then generating an anti-inductive magnetic field, so that the permanent magnet can rotate under the drive of the anti-inductive magnetic field.

2. The magnetic coupler for drilling according to claim 1, characterized in that: A gap (50) is provided between the conductor and the permanent magnet, and a liquid inlet (52) and a liquid outlet (54) communicating with the gap and the outside of the body are respectively provided on the body at the upper and lower ends of the gap, so that downhole fluid can flow through the body from between the conductor and the permanent magnet.

3. The magnetic coupler for drilling according to claim 2, characterized in that: An isolating cylinder (55) is also arranged in the gap, and the isolating cylinder is configured to separate the gap into an outer annular space (56) close to the conductor and an inner annular space (58) close to the permanent magnet. The liquid inlet and the liquid outlet are configured to communicate with the outer annular space.

4. The magnetic coupler for drilling according to claim 3, characterized in that: A first friction-reducing and drag-reducing element (60) connecting the conductor and the isolation cylinder is also arranged in the outer annulus.

5. The magnetic coupler for drilling according to claim 4, characterized in that: The outer walls at the upper and lower ends of the isolation cylinder are respectively provided with clamping grooves, and the first friction and resistance reducing element is fixedly arranged in the clamping grooves.

6. The magnetic coupler for drilling according to claim 4 or 5, characterized in that: The first friction and drag reducing element is configured as an angular contact ball bearing.

7. The magnetic coupler for drilling according to any one of claims 1 to 5, characterized in that: An upper joint (11) capable of connecting a drill rod is also arranged on the main body, and the permanent magnet is arranged to be fixedly connected to the inner wall of the main body.

8. The magnetic coupler for drilling according to any one of claims 1 to 5, characterized in that: The permanent magnet is also connected to a core shaft (35), the upper end of the core shaft is fixedly extended into the interior of the permanent magnet so that it can rotate synchronously under the drive of the permanent magnet, and the lower end of the core shaft is arranged to extend out of the body. A lower joint (36) capable of connecting a load is also arranged at the lower end of the core shaft.

9. The magnetic coupler for drilling according to claim 7, characterized in that: A sealing member (38) is also provided between the core shaft and the body.

10. The magnetic coupler for drilling according to any one of claims 3 to 5, characterized in that: The isolation cylinder is made of a non-magnetic alloy material, and the conductor is made of a metal material.

Images