Downhole active clutch with dual stage pressure lock

Abstract

The application provides a downhole active clutch with a double-stage pressure locking function, comprising a motor assembly and a clutch assembly, wherein the clutch assembly comprises a shell, a sliding dog, a drill bit connecting shaft and a fixed dog; the drill bit connecting shaft is connected to the lower end of the sliding dog and is circumferentially fixed with the sliding dog; and the fixed dog is circumferentially fixedly connected with the shell; in a first state, the sliding dog is circumferentially fixedly connected with the motor assembly and is disengaged from the fixed dog; the motor assembly can drive the sliding dog to rotate and drive the drill bit to rotate through the drill bit connecting shaft; in a second state, the sliding dog can descend relative to the shell and is disengaged from the motor assembly and can be engaged with the fixed dog; the shell can be driven to rotate by rotating the drill pipe through a rotary table arranged at a wellhead, and the drill bit is sequentially driven to rotate through the fixed dog, the sliding dog and the drill bit connecting shaft; and the first state and the second state can be switched with each other.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of drilling and completion operation tools, and particularly relates to a downhole active clutch with a two-stage pressure locking function. BACKGROUND

[0002] Modern oil drilling mostly adopts a screw drill assembly, that is, a motor assembly is combined in a drill string. The motor assembly is a positive displacement motor mainly composed of a rotor and a stator. The rotor is a spiral alloy steel shaft, and the stator is composed of an alloy steel pipe and an internally bonded rubber cavity. The motor assembly converts the pressure energy of drilling fluid into the energy of a drill bit. Influenced by the characteristics of the motor assembly, when the rock breaking torque is higher than the maximum torque of the screw, the motor assembly is stopped, the rotor cannot rotate, and the drilling fluid pressure rises to pierce the stator rubber. At this time, increasing the torque of the rotary table or the top drive will cause the stator to rotate relative to the rotor, but the torque cannot be applied to the drill bit. Drill bit jamming is prone to cause a stuck pipe accident, causing downhole complications, and even requiring a sidetrack to be drilled by cutting off the drill string, resulting in significant losses.

[0003] At present, with the continuous development of drilling technology, a screw motor clutch appears in the prior art, which realizes the switching of the two transmission routes of the screw motor driving drill bit and the rotary table driving drill bit. When the rotor is jammed, the rotary table continues to rotate the drill string and thus rotates the stator, so that the rotational speed of the stator relative to the rotor is greater than a certain value, the clutch is activated by centrifugal force and change of relative rotation direction, at this time the ground torque is transmitted to the drill bit through the stator, clutch device and rotor, and the drill bit jamming is released. However, the existing screw motor clutch can only be passively activated under certain conditions after the stuck pipe occurs, and the stuck pipe is released by the rotary table torque, and it cannot be actively activated as needed. The existing screw motor clutch cannot switch to the rotary table directly driving the drill bit before drilling into the stratum prone to stuck pipe or before drilling into the stratum with large torque, and thus it cannot achieve the technical effect of preventing stuck pipe. SUMMARY

[0004] In view of the above technical problems, the present application aims to provide a downhole active clutch with a two-stage pressure locking function, which can actively switch between the two transmission modes of the motor assembly driving the drill bit and the rotary table driving the drill bit as needed, and can prevent the stuck pipe caused by excessive drilling torque and release the stuck pipe after the stuck pipe occurs.

[0005] To this end, the application provides a downhole active clutch with a two-stage pressure locking function, comprising: a motor assembly; a clutch assembly connected to the lower end of the motor assembly, the clutch assembly comprising: a housing; a sliding dog arranged in the housing, the sliding dog being capable of moving along the axial direction of the housing; a drill bit connecting shaft for connecting a drill bit, the drill bit connecting shaft being connected to the lower end of the sliding dog and being circumferentially fixed with the sliding dog; and a fixed dog sleeved on the outer wall of the drill bit connecting shaft, the fixed dog being circumferentially fixedly connected with the housing; wherein, in a first state, the sliding dog is circumferentially fixedly connected with the motor assembly and is disengaged from the fixed dog, the motor assembly can drive the sliding dog to rotate and drive the drill bit to rotate through the drill bit connecting shaft, in a second state, the sliding dog can move downward relative to the housing to be disengaged from the motor assembly and can be engaged with the fixed dog, the housing can be driven to rotate by rotating the drill pipe through the turntable arranged at the wellhead, and the drill bit can be driven to rotate through the fixed dog, the sliding dog and the drill bit connecting shaft in turn, and the first state and the second state can be switched with each other.

[0006] In one embodiment, the clutch assembly further comprises a rotor connecting shaft configured as a hollow, the upper end of the rotor connecting shaft being connected with the motor assembly, the upper end of the sliding dog extending into the interior of the rotor connecting shaft, in the first state, the sliding dog is circumferentially fixedly connected with the rotor connecting shaft, the motor assembly can drive the rotor connecting shaft to rotate under the action of the drilling fluid, thereby driving the sliding dog to rotate, in the second state, the sliding dog moves downward relative to the rotor connecting shaft to be relatively rotatable with the rotor connecting shaft, thereby being disengaged from the motor assembly.

[0007] In one embodiment, the clutch assembly further comprises a pressure locking sleeve sleeved on the outer wall of the sliding dog, the outer wall of the sliding dog is provided with a step with an end face facing upward, the lower end face of the pressure locking sleeve abuts against the step, and a resilient member is further sleeved on the sliding dog, the two ends of the resilient member respectively abutting against the rotor connecting shaft and the pressure locking sleeve, in the second state, the resilient member can drive the pressure locking sleeve to drive the sliding dog to move downward relative to the rotor connecting shaft.

[0008] In one embodiment, the lower end of the pressure locking sleeve is provided with a plurality of pressure relief grooves extending along the axial direction, the plurality of pressure relief grooves are uniformly distributed in the circumferential direction, and a second locking sealing member is arranged on the inner wall of the housing, in the first state, the pressure relief grooves are located radially inside the second locking sealing member, in the second state, the outer wall of the pressure locking sleeve and the inner wall of the housing are sealed by the second locking sealing member.

[0009] In one embodiment, the outer wall of the sliding dog leg is provided with a first locking seal, and the sliding dog leg is capable of forming a seal with the inner wall of the housing through the first locking seal.

[0010] In one embodiment, the side wall of the housing is provided with a pressure transmission hole, a radial space is formed between the housing and the sliding dog leg, the pressure locking sleeve and the elastic member are arranged in the radial space, and the radial space is in communication with the wellbore annulus through the pressure transmission hole.

[0011] In one embodiment, the outer wall of the sliding dog leg is provided with a first torque transmission engagement surface, the inner wall of the rotor connecting shaft is provided with a second torque transmission engagement surface, the first torque transmission engagement surface is adaptedly engaged with the second torque transmission engagement surface in the first state, and the first torque transmission engagement surface is disengaged from the second torque transmission engagement surface in the second state.

[0012] In one embodiment, the inner wall of the lower end of the sliding dog leg is provided with a third torque transmission engagement surface, the outer wall of the drill bit connecting shaft is provided with a fourth torque transmission engagement surface, and the third torque transmission engagement surface is adaptedly engaged with the fourth torque transmission engagement surface, so that the drill bit connecting shaft and the sliding dog leg form a circumferential fixed connection.

[0013] In one embodiment, the lower end of the sliding dog leg is provided with a first dog leg portion, the upper end of the fixed dog leg is provided with a second dog leg portion, the first dog leg portion is disengaged from the second dog leg portion in the first state, and the first dog leg portion is adaptedly engaged with the second dog leg portion in the second state, so that the sliding dog leg and the fixed dog leg form a circumferential fixed connection.

[0014] In one embodiment, the outer periphery surface of the fixed dog leg is provided with an external spline, the inner wall of the housing is provided with an internal spline, and the external spline is adapted with the internal spline, so that the fixed dog leg and the housing form a circumferential fixed connection.

[0015] In one embodiment, the lower end of the fixed dog leg is provided with a positioning member, and the positioning member is capable of axially limiting the fixed dog leg.

[0016] In one embodiment, the lower end of the drill bit connecting shaft is provided with a drill bit joint for connecting a drill bit, the drill bit joint is rotatably connected with the housing through a transmission assembly, and the transmission assembly includes a transmission shaft and a transmission bearing set.

[0017] In one embodiment, the rotor connecting shaft and the housing are rotatably connected through a bearing assembly, and the rotor connecting shaft and the housing form a rotary seal through a first annular seal.

[0018] In one embodiment, the motor assembly comprises a motor housing, a stator cavity formed on an inner wall of the motor housing, and a rotor arranged in the motor housing, the rotor connecting shaft is connected with the rotor through a universal shaft, and the rotor can rotate under the action of the drilling fluid, thereby driving the rotor connecting shaft to rotate.

[0019] Compared with the prior art, the application has the advantages that:

[0020] The downhole active clutch with double-stage pressure locking function according to the application can actively switch between the motor assembly driving the drill bit and the rotary table driving the drill bit according to the actual working condition, and can prevent the drill pipe from being stuck due to excessive drilling torque and can release the stuck drill pipe. The downhole active clutch drives the sliding dog to move by changing the spring force and the drilling fluid pressure, changes the engagement state of the multiple sets of torque transmission structures, drives the drill bit to drill by the motor assembly in normal drilling, and drives the drill bit to drill by the drill pipe in the case of requiring large torque, which is very beneficial to drilling operation and improves the operation efficiency. Moreover, the downhole active clutch can stably maintain the engagement or disengagement state under the normal displacement by the double-stage locking and sealing structure. The downhole active clutch can realize the engagement of the clutch by the composite operation of "stopping the pump, increasing the drilling pressure, and rotating the drill string", and can realize the disengagement of the clutch by "lifting the drill string from the bottom, and using the large displacement", which can effectively prevent the downhole active clutch from being misoperated. In the operation process, the action state of the downhole active clutch can be determined by the discharge of the drilling fluid in the drill pipe and the change of the torque, the state of the downhole active clutch can be actively controlled, and the transmission route can be changed as required. The downhole active clutch can be actively activated by the ground operation, is not affected by the change of the drilling parameters, can be switched to the rotary table directly driving the drill bit before drilling into the stratum prone to being stuck or before drilling into the stratum with large torque, can prevent the drill pipe from being stuck, and can reduce the cost and improve the efficiency. The rotors of the motor assembly before and after the engagement of the downhole active clutch can rotate, the inside of the drill string is kept unobstructed, and the drilling fluid circulation is not affected. The large-torque transmission structure is arranged on the housing, can transmit large torque, and the rotors are not affected by the torque. The downhole active clutch can be integrated as a module in the existing screw motor, the clutch can be controlled by the conventional drilling action combination, and the screw motor structure and the ground equipment do not need to be modified. BRIEF DESCRIPTION OF DRAWINGS

[0021] The application will be described below with reference to the drawings.

[0022] Figure 1 The structure of the downhole active clutch with double-stage pressure locking function according to the application is shown.

[0023] Figure 2 The structure of the downhole active clutch with double-stage pressure locking function according to the application is shown. Figure 1 The structure of the rotor connecting shaft in the downhole active clutch is shown.

[0024] Figure 3 The structure of the downhole active clutch with double-stage pressure locking function according to the application is shown.Figure 1 The structure of the sliding teeth in the downhole active clutch is shown.

[0025] Figure 4 Shows Figure 1 The structure of the pressure locking sleeve in the downhole active clutch is shown.

[0026] Figure 5 Shows Figure 1 The structure of the fixed teeth in the downhole active clutch is shown.

[0027] Figure 6 Shows Figure 1 The structure of the housing in the downhole active clutch is shown.

[0028] Figure 7 Shows Figure 1 The structure of the drill bit connecting shaft in the downhole active clutch is shown.

[0029] Figure 8 and Figure 9 The figure shows the state of the downhole active clutch in the double-stage seal switching process.

[0030] Figure 10 The engagement status of the downhole active clutch is shown.

[0031] In this application, all drawings are schematic drawings, which are only used to illustrate the principles of the present invention and are not drawn to scale. DETAILED DESCRIPTION

[0032] The present invention will be described below with reference to the accompanying drawings.

[0033] Figure 1 FIG. 1 shows the structure of a downhole active clutch 100 with a dual-stage pressure locking function according to the present invention. Figure 1 As shown, the downhole active clutch 100 includes a motor assembly and a clutch assembly connected to the lower end of the motor assembly, as well as a transmission assembly 10 connected to the lower end of the clutch assembly, which is used to connect to the drill bit. The downhole active clutch 100 is configured to control the pumping displacement and thus the pressure in the drill pipe as needed, thereby actively switching between two transmission modes: the motor assembly drives the drill bit and the rotary drive drives the drill bit. This prevents excessive drilling torque from causing the drill bit to get stuck, and also helps release the stuck drill bit. Specifically, when the clutch assembly is in the disengaged state, the downhole active clutch 100 drives the drill bit to drill through the motor assembly. At this time, the downhole active clutch 100 is in the first state. When the clutch assembly is in the engaged state, the downhole active clutch 100 drives the drill bit to drill through the rotary drive or top drive. At this time, the downhole active clutch 100 is in the second state.

[0034] like Figure 1As shown, the motor assembly comprises a motor housing 11, a stator cavity 111 formed on the inner wall of the motor housing 11 and a rotor 112 arranged in the motor housing 11, the rotor 112 being capable of rotating relative to the stator cavity 111 under the action of the drilling fluid.

[0035] According to the present application, as Figure 1 As shown, the downhole active clutch 100 comprises a hollow rotor connecting shaft 1, a housing 3, a sliding dog 4 arranged in the housing 3, a drill bit connecting shaft 6 for connecting a drill bit, and a fixed dog 7 sleeved on the drill bit connecting shaft 6. The sliding dog 4 is capable of moving along the axial direction of the housing 3. The drill bit connecting shaft 6 is connected to the lower end of the sliding dog, and the drill bit connecting shaft 6 is in circumferential fixed connection with the sliding dog 4. The fixed dog 7 is in circumferential fixed connection with the housing 3. The housing 3 is in the shape of a cylinder, and is used for maintaining the relative positions of the parts and moving along the designed trajectory, and in the process of driving the drill bit by the rotary table (in the second state), the housing 3 can transmit the drill pipe torque to the fixed dog 7.

[0036] In one embodiment, the upper end of the housing 3 is in fixed connection with the motor housing 11 by screw connection. The upper end of the rotor connecting shaft 1 is connected with the rotor 112 by a universal shaft 113. For example, the upper end of the rotor connecting shaft 1 is in fixed connection with the universal shaft 113 by screw connection.

[0037] As Figure 2 As shown, the rotor connecting shaft 1 is in the shape of a hollow pipe, and the upper end of the rotor connecting shaft 1 is provided with an annular protrusion extending radially outward. A first annular sealing member 103 is arranged on the outer wall of the rotor connecting shaft 1 near the middle part. The upper end of the housing 3 is inserted into the motor housing 11. The rotor connecting shaft 1 is insertedly arranged in the housing 3, and a bearing assembly 2 is arranged between the lower end surface of the annular protrusion and the upper end surface of the housing 3. The bearing assembly 2 is used for bearing the axial force and the radial force of the rotor connecting shaft 1, so that the rotor connecting shaft 1 can rotate relative to the housing 3. In addition, the first annular sealing member 103 is arranged between the contact surface of the rotor connecting shaft 1 and the inner wall of the housing 3, which can effectively ensure the sealing between the rotor connecting shaft 1 and the housing 3.

[0038] According to the present application, Figure 3 The structure of the sliding dog 4 is shown. As Figure 3As shown, an axially extending flow channel for liquid to flow through is provided inside the sliding tooth ridge 4. The sliding tooth ridge 4 is constructed to include a cylindrical first part and a second part connected to the lower end of the first part, and the diameter of the first part is smaller than the diameter of the second part. Thus, a step with the end face facing upward is formed at the connection between the first part and the second part. The upper end part of the sliding tooth ridge 4 extends to the interior of the rotor connecting shaft 1, and the sliding tooth ridge 4 can move axially along the rotor connecting shaft 1. A second annular seal 401 is provided on the outer wall of the first part near the upper end. The second annular seal 401 is located between the contact surface of the sliding tooth ridge 4 and the inner wall of the rotor connecting shaft 1, which can effectively ensure the sealing between the sliding tooth ridge 4 and the rotor connecting shaft 1.

[0039] like Figure 3 As shown, a first torque transmission interface 402 is provided on the outer wall surface of the first portion of the sliding tooth ridge 4. The first torque transmission interface 402 is located a certain distance from the upper end surface of the sliding tooth ridge 4, thereby leaving a cylindrical portion at the upper end of the first torque transmission interface 402. Simultaneously, a second torque transmission interface 102 is provided on the inner wall of the rotor connecting shaft 1, located near the inner wall of the rotor connecting shaft 1 near the lower end surface. The first torque transmission interface 402 and the second torque transmission interface 102 are configured to form a compatible torque transmission structure, such as a spline, hexagonal, or tooth ridge structure. The upper end of the sliding tooth ridge 4 extends into the interior of the rotor connecting shaft 1, and the sliding tooth ridge 4 is able to move axially along the rotor connecting shaft 1. In the first state, the first torque transmission interface 402 and the second torque transmission interface 102 are adaptively engaged, so that the sliding tooth ridge 4 and the rotor connecting shaft 1 are circumferentially fixed. In the second state, the first torque transmission joint surface 402 is disengaged from the second torque transmission joint surface 102 , so that the sliding tooth 4 can rotate relative to the rotor connecting shaft 1 .

[0040] In this embodiment, a first locking seal 404 is provided on the outer wall of the second portion of the sliding tooth 4, and the first locking seal 404 is arranged near the upper end surface of the second portion. The sliding tooth 4 can be positively locked with the inner wall surface of the housing 3 to form a seal through the first locking seal 404.

[0041] According to the present invention, the clutch assembly further includes a pressure-locking sleeve 9 mounted on the outer wall of the sliding tooth 4. The lower end surface of the pressure-locking sleeve 9 abuts against a step on the outer wall of the sliding tooth 4. An elastic member 5 is also mounted on the sliding tooth 4. Its two ends abut against the lower end surface of the rotor connecting shaft 1 and the upper end surface of the pressure-locking sleeve 9, respectively. In one embodiment, the elastic member 5 can be a compression spring. In the second state, the elastic member 5 generates a spring force that drives the pressure-locking sleeve 9, causing the sliding tooth 4 to move downward relative to the rotor connecting shaft 1.

[0042] likeFigure 4 As shown, the upper end of the pressure locking sleeve 9 is constructed as a flange-like structure, against which the lower end of the elastic member 5 abuts. The lower end of the pressure locking sleeve 9 is provided with a plurality of pressure relief grooves 901 extending axially from the axial end surface. These grooves 901 are evenly distributed along the circumference. The function of these grooves 901 will be described below.

[0043] According to the present invention, a radial space is formed between the housing 3 and the sliding tooth ridge 4, and the pressure locking sleeve 9 and the elastic member 5 are arranged in the radial space. A pressure transmission hole 303 (see FIG. 1 ) is provided on the side wall of the housing 3 corresponding to the radial space. Figure 6 ), the radial space is connected to the wellbore annulus through the pressure transmission hole 303.

[0044] In this embodiment, a third annular seal 403 is further provided on the outer wall of the first portion of the sliding tooth ridge 4. The third annular seal 403 is disposed axially inwardly of the first torque transmission interface 402. The third annular seal 403 is positioned between the contact surface of the sliding tooth ridge 4 and the pressure locking sleeve 9, thereby forming a seal between the sliding tooth ridge 4 and the pressure locking sleeve 9.

[0045] According to the present invention, a radially inward annular boss is provided on the inner wall of the housing 3 (see Figure 6 ), a second locking seal 301 is provided on the inner wall of the annular boss. A shoulder with the end face facing downward is provided on the inner wall of the shell 3 near the lower position of the annular boss. In the first state, the step of the sliding tooth ridge 4 contacts the lower end face of the annular boss, and the pressure relief groove 901 is correspondingly located on the radial inner side of the second locking seal 301, and the first locking seal 404 is located on the upper part of the shoulder and forms a locking seal with the side wall of the shell 3. In the second state, the pressure locking sleeve 9 moves downward relative to the shell 3, so that the outer wall of the pressure locking sleeve 9 and the inner wall of the shell 3 form a locking seal through the second locking seal 301, and the first locking seal 404 moves downward to cross the shoulder, thereby rendering the seal between the sliding tooth ridge 4 and the shell 3 ineffective.

[0046] Figure 5 The structure of the fixed tooth ridge 7 is shown. Figure 5 As shown, the fixed tooth ridge 7 is constructed into a cylindrical shape, and the outer peripheral surface of the fixed tooth ridge 7 is provided with an external spline 702. At the same time, the inner wall surface of the housing 3 is provided with an internal spline 302 (see Figure 6 ), the inner spline 302 is arranged near the lower end of the housing 3. The fixed tooth ridge 7 is arranged in the housing 3, and is adapted to be installed with the outer spline 702 and the inner spline 302, so that the fixed tooth ridge 7 and the housing 3 form a circumferential fixed connection.

[0047] According to the present invention, Figure 5As shown, a second ridge portion 701 is arranged at the upper end of the fixed ridge 7. Meanwhile, a first ridge portion 405 is arranged at the lower end of the sliding ridge 4 (see Figure 3 ). In the first state, the first ridge portion 405 is disengaged from the second ridge portion 701. In the second state, the sliding ridge 4 is lowered relative to the housing 3, so that the first ridge portion 405 can be engaged with the second ridge portion 701, thereby enabling the sliding ridge 4 to be fixedly connected with the fixed ridge 7 in the circumferential direction. In addition, the drill bit connecting shaft 6 is connected with the sliding ridge 4 through the fixed ridge 7, and the fixed ridge 7 can rotate relative to the drill bit connecting shaft 6.

[0048] In one embodiment, a positioning member 8 is arranged at the lower end of the fixed ridge 7. Preferably, the positioning member 8 can be a positioning spring. The positioning member 8 can axially limit the fixed ridge 7, so as to keep the fixed ridge 7 in a certain position and prevent the fixed ridge 7 from moving in the circumferential direction. Meanwhile, the positioning member 8 can compensate for axial assembly errors.

[0049] Figure 7 The structure of the drill bit connecting shaft 6 is shown. As shown in Figure 7 , the drill bit connecting shaft 6 is configured in a cylindrical shape, and a fourth torque transmission joint surface 601 is arranged on the outer wall of the drill bit connecting shaft 6. The fourth torque transmission joint surface 601 is arranged to extend axially inward from the upper end surface of the drill bit connecting shaft 6. Meanwhile, a third torque transmission joint surface 406 is arranged on the inner wall of the lower end of the sliding ridge 4 (see Figure 1 ). The third torque transmission joint surface 406 and the fourth torque transmission joint surface 601 are configured as torque transmission structures that are adapted to each other. For example, the structures can be splines, hexagons, ridges, etc. In this way, the sliding ridge 4 and the drill bit connecting shaft 6 are fixedly connected in the circumferential direction.

[0050] During the operation of the downhole active clutch 100, the upper end of the sliding ridge 4 is connected with the rotor connecting shaft 1 through the upper torque transmission structure formed by the first torque transmission joint surface 402 and the second torque transmission joint surface 102, and the lower end of the sliding ridge 4 is connected with the fixed ridge 7 through the lower torque transmission structure formed by the third torque transmission joint surface 406 and the fourth torque transmission joint surface 601. The upper torque transmission structure and the lower torque transmission structure can be switched by the axial movement of the sliding ridge 4.

[0051] According to the present application, as Figure 1As shown, a drill bit connector 101 is arranged at the lower end of the drill bit connecting shaft 6, and is used to connect a drill bit or other output device. The drill bit connector 101 is rotationally connected with the housing 3 through a transmission assembly 10. The transmission assembly 10 includes a transmission shaft and a transmission bearing set. In one embodiment, the transmission shaft is configured as a hollow shaft, including a first shaft body and a second shaft body fixedly connected with the first shaft body. An outer limiting step and an inner limiting step are formed at the connection between the first shaft body and the second shaft body, with the end face of the outer limiting step facing upward and the end face of the inner limiting step facing downward. An outer thread is arranged on the outer wall of the first shaft body, and is fixedly connected with the inner wall of the lower end of the housing 3 through a threaded connection, with the end face of the outer limiting step in contact with the lower end face of the housing 3. An installation step with an upward facing end face is arranged on the outer wall of the drill bit connector 101, and the upper end of the drill bit connector 101 is fixedly connected with the drill bit connecting shaft 6 through a threaded connection. The transmission bearing set is arranged between the transmission shaft and the drill bit connector 101, with the upper and lower ends of the transmission bearing set abutting against the inner limiting step and the installation step, respectively. In this way, the drill bit connector 101 is rotationally connected with the housing 3 through the transmission assembly 10.

[0052] The working process of the downhole active clutch 100 with the double-stage pressure locking function according to the present application is briefly described below. Figure 1 For the structure of the downhole active clutch 100 in the disengaged state, it is assumed that the initial state of the downhole active clutch 100 is the disengaged state (first state). It can be understood that the initial state of the downhole active clutch 100 can be the engaged state through modification of the design.

[0053] As Figure 1As shown, in the initial state, the downhole active clutch 100 is in the first state. During drilling, the first torque transmission engagement surface 402 of the sliding dog 4 is engaged with the second torque transmission engagement surface 102 of the rotor connecting shaft 1. The rotor 112 of the motor assembly rotates under the pressure of the drilling fluid, and drives the rotor connecting shaft 1 to rotate through the universal shaft 113, and the rotor connecting shaft 1 drives the sliding dog 4 to rotate through the upper torque transmission structure formed by the first torque transmission engagement surface 402 and the second torque transmission engagement surface 102, and the sliding dog 4 drives the drill bit connecting shaft 6 to rotate through the lower torque transmission structure formed by the third torque transmission engagement surface 406 and the fourth torque transmission engagement surface 601, and then drives the drill bit joint 101 to rotate, so as to transmit the torque of the rotor 112 to the drill bit. At this time, the sliding dog 4 is sealed between the first locking seal 404 and the inner wall of the housing 3, and the upper pressure of the first locking seal 404 is communicated with the annulus through the pressure transmission hole 303, and the lower pressure is equal to the internal pressure of the drill pipe. Since the outer diameter of the first locking seal 404 is larger than the outer diameter of the second locking seal 301, a higher force is generated due to the pressure difference between the inside and outside of the drill pipe, so that the elastic member 5 can be kept in a fully compressed state to prevent the sliding dog 4 from moving downward to engage with the fixed dog 7. The downhole active clutch 100 is in the first state. Thus, the motor assembly drives the drill bit to drill.

[0054] During the drilling operation, when the downhole active clutch 100 needs to be engaged when drilling a large torque formation or the drill bit is stuck, mud is stopped from being pumped into the drill string, and a low drilling pressure is applied to the drill bit to prevent the drill bit from rotating when the clutch is actuated. At this time, the drill bit is stationary, and the drill bit joint 101, the drill bit connecting shaft 6, the sliding dog 4, the rotor connecting shaft 1, the universal shaft 113, and the rotor 112 cannot rotate. The elastic member 5 pushes the pressure locking sleeve 9 to press down the sliding dog 4 under the elastic force. The drilling fluid in the radial annulus of the wellbore flows into the upper space of the first locking seal 404 through the pressure transmission hole 303 and the pressure relief groove 901. When the seal between the first locking seal 404 and the housing 3 fails, the pressure relief groove 901 of the pressure locking sleeve 9 moves to the lower side of the second locking seal 301, and the outer wall of the pressure locking sleeve 9 forms a seal with the second locking seal 301 to prevent the pressure inside the drill pipe from communicating with the outside. Figure 8 and Figure 9 The two-stage sealing switching process of the downhole active clutch 100 is shown.

[0055] The sliding dog 4 descends under the elastic force of the elastic member 5 until it contacts the fixed dog 7. The first dog part 405 is engaged with the second dog part 701 of the fixed dog 7, Figure 9The first toothed portion 405 of the sliding toothed cam 4 is shown disengaged from the second toothed portion 701 of the fixed toothed cam 7. By rotating the drill string in the positive direction, the drill string drives the housing 3 to rotate in the positive direction, and in turn drives the fixed toothed cam 7 to rotate in the positive direction, until the first toothed portion 405 at the lower end of the sliding toothed cam 4 is aligned with the second toothed portion 701 of the fixed toothed cam 7. The first toothed portion 405 is then engaged with the second toothed portion 701 under the elastic force of the elastic member 5. At the same time, the first torque transmission interface 402 at the upper end of the sliding toothed cam 4 is disengaged from the second torque transmission interface 102 of the rotor connecting shaft 1. Figure 10 The engagement state of the downhole active clutch 100 is shown. At this time, the drill pipe torque is transmitted to the fixed toothed cam 7 through the housing 3, and in turn to the sliding toothed cam 4, and then to the drill bit connecting shaft 6. Since the drill bit is stationary, the housing 3 rotates, and the stator gel cavity 111 and the rotor 112 of the motor assembly rotate in opposite directions, and the motor assembly generates a pumping effect. By whether or not liquid is returned from the drill pipe and the amount of liquid discharged, it can be determined whether the downhole active clutch 100 is in action and the completion of the action. When the sliding toothed cam 4 is engaged with the fixed toothed cam 7, the drill pipe torque suddenly increases, and the change in torque can be used to determine whether the downhole active clutch 100 is engaged.

[0056] After the downhole active clutch 100 is engaged, the pump is opened at the normal drilling displacement, and drilling continues. At this time, since the outer diameter of the second locking seal 301 is smaller than the outer diameter of the first locking seal 404, the force generated by the pressure difference between the inside and outside of the drill pipe is low, and the elastic member 5 cannot be compressed. The spring force of the elastic member 5 can prevent the sliding toothed cam 4 from moving upward and disengaging from the fixed toothed cam 7. In this way, the rotary table drive is used to drive the drill bit to drill. At this time, the rotor 112 of the motor assembly rotates freely, keeping the drill string unobstructed and having no effect on the drilling fluid circulation.

[0057] When it is needed to separate the downhole active clutch 100 and convert to motor assembly driving drilling, the drilling tool is lifted off the bottom of the well, and the drilling fluid discharge is increased to 150%-200% of the normal discharge. With the increase of the discharge, the pressure difference on both sides of the second locking seal 301 increases until the pushing pressure moves the pressure locking sleeve 9 up to compress the elastic member 5, and the pressure locking sleeve 9 moves up together with the sliding dog 4 through the friction of the third annular seal 403. When the first locking seal 404 reseals with the housing 3, the pressure difference between the inside and outside of the drill pipe is blocked by the first locking seal 404, the pressure difference acting surface is increased, and the second locking seal 301 is disabled due to the communication of the pressure relief groove 901. The differential pressure force further compresses the elastic member 5, and the first dog part 405 of the sliding dog 4 is separated from the second dog part 701 of the fixed dog 7. At the same time, the first torque transmission joint surface 402 of the sliding dog 4 and the second torque transmission joint surface 102 of the rotor connecting shaft 1 are re-adapted and engaged. The rotor 112 of the motor assembly drives the rotor connecting shaft 1 to rotate, the rotor connecting shaft 1 drives the sliding dog 4 to rotate, and then the sliding dog 4 drives the drill bit connecting shaft 6 to rotate, thereby converting to the motor assembly driving drill bit drilling state. At this time, the circulating discharge is reduced to the normal drilling discharge, and since the pressure difference acting on the first locking seal 404 is greater than the elastic force of the elastic member 5, the sliding dog 4 and the rotor connecting shaft 1 are combined to ensure that the motor assembly driving drilling is carried out according to the normal drilling parameters.

[0058] The downhole active clutch 100 with the double-stage pressure locking function according to the present application can actively switch between the motor assembly driving the drill bit and the rotary table driving the drill bit according to the actual working condition, and realize the functions of preventing the drill string from being stuck due to excessive torque and releasing the stuck drill string. The downhole active clutch 100 drives the sliding dog to move by the change between the spring force and the drilling fluid pressure, changes the engagement state of the multiple sets of torque transmission structures, realizes the drill bit drilling by the motor assembly in the normal drilling, and realizes the drill bit drilling by the drill pipe in the case of requiring large torque, which is very beneficial to the drilling operation and improves the operation efficiency. Moreover, the downhole active clutch 100 can stably maintain the engagement or separation state under the normal displacement by the double-stage locking sealing structure. The downhole active clutch 100 realizes the engagement of the clutch by the composite operation of "stopping the pump, adding the drilling pressure, and rotating the drill string", realizes the separation of the clutch by "lifting the drill string from the bottom and using the large displacement", and can effectively prevent the downhole active clutch 100 from being misoperated. In the operation process, the action state of the downhole active clutch 100 is judged by the discharge of the drilling fluid in the drill pipe and the change of the torque, the state of the downhole active clutch 100 can be actively controlled, and the transmission route can be changed according to the need. The downhole active clutch 100 can be actively activated by the ground operation, is not affected by the change of the drilling parameters, can be switched to the rotary table directly driving the drill bit before drilling into the stratum prone to being stuck or before drilling into the stratum with large torque, prevents the drill string from being stuck, and reduces the cost and improves the efficiency. The rotor 112 of the motor assembly can rotate before and after the engagement of the downhole active clutch 100, so as to keep the drill string unblocked and has no influence on the drilling fluid circulation. The large torque transmission structure is arranged on the housing 3, can transmit large torque, and makes the rotor 112 not affected by the torque. The downhole active clutch 100 can be integrated as a module in the existing screw motor, controls the clutch by the conventional drilling action combination, and does not need to modify the screw motor structure and the ground equipment.

[0059] Finally, it should be noted that the above only describes the preferred embodiments of the present application and does not constitute any limitation on the present application. Although the present application is described in detail with reference to the foregoing embodiments, the skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or replace some technical features with equivalent ones. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. Downhole active clutch with dual-stage pressure locking function, including: Motor assembly; A clutch assembly connected to the lower end of the motor assembly, the clutch assembly comprising: Housing (3); A sliding tooth ridge (4) is arranged in the housing, and the sliding tooth ridge is capable of moving along the axial direction of the housing; a drill bit connecting shaft (6) for connecting a drill bit, the drill bit connecting shaft being connected to the lower end of the sliding tooth ridge and being circumferentially fixed to the sliding tooth ridge; and A fixed tooth ridge (7) is sleeved on the outer wall of the drill bit connecting shaft, wherein the fixed tooth ridge forms a circumferential fixed connection with the housing; In the first state, the sliding tooth ridge is circumferentially fixedly connected to the motor assembly and is separated from the fixed tooth ridge. The motor assembly can drive the sliding tooth ridge to rotate and drive the drill bit to rotate through the drill bit connecting shaft. In the second state, the sliding tooth ridge can move downward relative to the housing and disengage from the motor assembly, and can be adapted to engage with the fixed tooth ridge. The housing can be driven to rotate by rotating the drill pipe through a turntable provided at the wellhead, and the drill bit can be driven to rotate in turn through the fixed tooth ridge, the sliding tooth ridge and the drill bit connecting shaft. The first state and the second state can switch between each other. The clutch assembly further comprises a hollow rotor connecting shaft (1), the upper end of the rotor connecting shaft being connected to the motor assembly, and the upper end of the sliding tooth extending into the interior of the rotor connecting shaft. In the first state, the sliding tooth ridge forms a circumferential fixed connection with the rotor connecting shaft, and the motor assembly can drive the rotor connecting shaft to rotate under the action of drilling fluid, thereby driving the sliding tooth ridge to rotate. In the second state, the sliding tooth edge moves downward relative to the rotor connecting shaft and can rotate relative to the rotor connecting shaft, thereby disengaging from the motor assembly.

2. The downhole active clutch according to claim 1, characterized in that: The clutch assembly further comprises a pressure locking sleeve (9) sleeved on the outer wall of the sliding tooth ridge, the outer wall of the sliding tooth ridge being provided with a step with an end surface facing upwards, and the lower end surface of the pressure locking sleeve abuts against the step. An elastic member (5) is also sleeved on the sliding tooth ridge, with two ends of the elastic member respectively abutting against the rotor connecting shaft and the pressure locking sleeve. In the second state, the elastic member can drive the pressure locking sleeve to drive the sliding tooth ridge downward relative to the rotor connecting shaft.

3. The downhole active clutch according to claim 2, characterized in that: The lower end of the pressure locking sleeve is provided with a plurality of pressure relief grooves (901) extending along the axial portion, and the plurality of pressure relief grooves are evenly distributed in the circumferential direction. A second locking seal (301) is provided on the inner wall of the shell. In the first state, the pressure relief groove is located radially inward of the second locking seal. In the second state, the outer wall of the pressure locking sleeve and the inner wall of the housing form a seal through the second locking seal.

4. The downhole active clutch according to any one of claims 1 to 3, characterized in that: The outer wall of the sliding tooth ridge is provided with a first locking seal (404), and the sliding tooth ridge can form a seal with the inner wall surface of the shell through the first locking seal.

5. The downhole active clutch according to claim 2 or 3, characterized in that: A pressure transmission hole (303) is provided on the side wall of the shell, a radial space is formed between the shell and the sliding tooth ridge, the pressure locking sleeve and the elastic member are arranged in the radial space, and the radial space is connected to the wellbore annulus through the pressure transmission hole.

6. The downhole active clutch according to claim 1, characterized in that: A first torque transmission joint surface (402) is provided on the outer wall of the sliding tooth ridge, and a second torque transmission joint surface (102) is provided on the inner wall of the rotor connecting shaft. In a first state, the first torque transmission engagement surface is adaptively engaged with the second torque transmission engagement surface. In the second state, the first torque transmission engagement surface is disengaged from the second torque transmission engagement surface.

7. The downhole active clutch according to claim 6, characterized in that: A third torque transmission joint surface (406) is provided on the inner wall of the lower end of the sliding tooth ridge, and a fourth torque transmission joint surface (601) is provided on the outer wall of the drill bit connecting shaft. The third torque transmission joint surface is adaptively engaged with the fourth torque transmission joint surface, thereby forming a circumferential fixed connection between the drill bit connecting shaft and the sliding tooth ridge.

8. The downhole active clutch according to claim 6 or 7, characterized in that: The lower end of the sliding tooth ridge is provided with a first tooth ridge portion (405), and the upper end of the fixed tooth ridge is provided with a second tooth ridge portion (701). In the first state, the first tooth ridge portion is separated from the second tooth ridge portion. In the second state, the first tooth ridge portion is adapted to engage with the second tooth ridge portion, so that the sliding tooth ridge can form a circumferential fixed connection with the fixed tooth ridge.

9. The downhole active clutch according to claim 1, characterized in that: The outer peripheral surface of the fixed tooth ridge is provided with an external spline (702), and the inner wall of the shell is provided with an internal spline (302), and the external spline can be adapted to the internal spline, so that the fixed tooth ridge and the shell form a circumferential fixed connection.

10. The downhole active clutch according to claim 9, characterized in that: A positioning piece (8) is provided at the lower end of the fixed tooth ridge, and the positioning piece can form an axial limit for the fixed tooth ridge.

11. The downhole active clutch according to claim 1, characterized in that: A drill bit joint (101) for connecting a drill bit is provided at the lower end of the drill bit connecting shaft, and the drill bit joint is rotationally connected to the housing via a transmission assembly (10), wherein the transmission assembly comprises a transmission shaft and a transmission bearing group.

12. The downhole active clutch according to claim 1, characterized in that: The rotor connecting shaft and the housing are rotationally connected via a bearing assembly (2), and the rotor connecting shaft and the housing are rotationally sealed via a first annular seal (103).

13. The downhole active clutch according to claim 1, characterized in that: The motor assembly comprises a motor housing (11), a stator rubber cavity (111) formed on the inner wall of the motor housing, and a rotor (112) disposed in the motor housing. The rotor connecting shaft is connected to the rotor via a universal shaft (113), and the rotor can rotate under the action of drilling fluid, thereby driving the rotor connecting shaft to rotate.

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