Tubing strings, such as drillpipes and casing, are deployed into a wellbore during operations to drill and case the wellbore. It may also be necessary to remove the tubing strings from the wellbore during operation. Intervention operations (e.g., fishing a broken or stuck tubular or tool) and workover operations also require deploying and removing tubing strings.
When a tubing string is being run into or pulled from the wellbore, it is often necessary to fill the tubing string with fluid (e.g., mud), to take fluid returns from the tubular string, or to circulate fluid (e.g., mud) through the tubular string. To establish fluid communication between the rig and the tubing string, a portion of a top drive can be threaded to the tubular string, a portion of the top drive can be at least partially inserted into the tubing string, or a circulation head can be connected to the tubing string.
Usually, a mud saver valve is used at the fluid connection to prevent spillage of fluid (i.e., mud) when the components for the fluid connection (e.g., top drive/Kelly hose or circulation head) are disconnected from the tubing string. As expected, the mud saver valve can prevent the loss of mud, can prevent unsafe operating conditions for personnel, and can minimize contamination of the environment.
To make the fluid connection, precise spacing is required for a seal assembly on the components used to establish the fluid communication with the tubing string. Typically, the end of the tubing string is supported by an elevator on the top drive. The elevator can be a slip-type elevator or can be a “side door” or a latching elevator. The seal assembly on the top drive is then brought into sealing engagement with the tubing string. Also, the main shaft (e.g., quill) of the top drive can be threaded to the tubing string.
A mechanical stroke tool can be used to make the connection between the top drive and the tubing string. The mechanical stroke tool can be extended by the rotation of the top drive's quill so the fluid connection can be made between the top drive and the tubing string. To unmake the connection, the mechanical stroke tool can also be retracted by the reverse rotation of the top drive's quill.
During these operations, however, the rotation of the top drive must be stopped at a predefined position to avoid damage to the mechanical stroke, its seals, and its thread mechanism. This applies to both the retracting and extending directions. The driller relies on visual markings (e.g., tape) on the bails of the top drive to show the positions for maximum extension and retraction of the tool. In some instances, the driller may over-extended and over-retract the stroke of the mechanical stroke tool, which can damage the tool. As expected, replacing the damaged tool can cause extended downtime on the rig.
The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
A flowback tool disclosed herein is used on a top drive for delivering fluid flow to a tubular. The flowback tool comprises a mechanical stroke tool and a clutch. The mechanical stroke has an inner body and an outer body with the inner body disposed in the outer body. The inner body is rotatable about an axis, and the outer body is movable in a stroke direction along the axis. For example, the outer body or barrel of the mechanical stroke can be moved by a cam/threaded engagement as the inner body or mandrel is rotated.
The inner body has a flow passage therethrough between a connection and a coupling. The connection is configured to connect to the top drive, and the coupling is configured to removably thread to the tubular. The flow passage has a valve configured to control fluid communication between the coupling and the connection. A first end of the outer body is disposed toward the connection, and a second end is disposed toward the coupling. The second end has an annular seal configured to sealably engage with the tubular.
The clutch has first and second portions, which define an interface with a torque threshold. The first portion is fixed on the outer body of the mechanical stroke, and the second portion has a disengaged condition and an engaged condition. The second portion in the engaged condition is configured to engage with a portion of the top drive, and the second portion in the engaged condition is configured to move with the first portion up to the torque threshold. The second portion in the engaged condition is configured to slip relative to the first portion beyond the torque threshold.
In one configuration, the first portion of the clutch can comprise a housing, a first brake pad, and a second brake pad. The housing has first and second shoulders and is fixed to the outer body of the mechanical stroke. The first brake pad is disposed in the housing adjacent to the first shoulder, and the first brake pad is configured to rotate with the housing. The second brake pad is disposed in the housing adjacent to the second shoulder, and the second brake pad is configured to rotate with the housing. One or more biasing elements are configured to bias the first brake pad away from the first shoulder.
Meanwhile, in this configuration, the second portion of the clutch can comprise a slip ring and an arm. The slip ring is disposed in the housing and has first and second surfaces. The first surface is engaged with the first brake, and the second surface is engaged with the second brake. The first and second surfaces engaged with the first and second brakes defines the interface with the torque threshold. The arm is connected to the slip ring. The arm is configured to extend radially outward from the slip ring to engage with the portion of the top drive, such as a bail of the top drive.
In another configuration, the first portion of the clutch can comprise a housing and a slip ring. The housing has a first shoulder, and the slip ring has a second shoulder. The housing and the slip ring are fixed on the outer body of the mechanical stroke. One or more biasing elements are configured to bias the first shoulder of the housing toward the second shoulder of the slip ring. Meanwhile, the second portion of the clutch can comprise a rotatable brake ring having first and second brake pads. The first and second brake pads are configured to engage the first and second shoulders respectively and define the interface with the torque threshold. The rotatable brake ring has the disengaged condition and the engaged condition. For instance, the rotatable brake ring in the engaged condition is configured to engage with the portion of the top drive so that the rotatable brake ring is configured to move with the housing and the slip ring of the first portion up to the torque threshold. However, the rotatable brake ring in the engaged condition is configured to slip relative to the housing and the slip ring of the first portion beyond the torque threshold.
A clutch is disclosed herein and is used on a top drive having a rotatable component and a bail. The clutch comprises a first portion and a second portion as described above.
A top drive is disclosed herein and is used for delivering fluid flow to a tubular. The top drive comprises: a quill extending from the top drive; bails supported on the top drive on either side of the quill; an elevator supported on the bails and configured to support the tubular; and a flowback tool, as described above, connected to the quill.
A method disclosed herein comprises: supporting a tubular in an elevator of a top drive; extending a barrel of a flowback tool relative to a mandrel of the flowback tool by rotating the mandrel in a first direction with the top drive while preventing rotation of the barrel with a clutch; establishing a fluid connection between the mandrel and the tubular by engaging a seal on the barrier in sealed engagement with an end of the tubular; and permitting the barrel to rotate in the first direction with the rotation of the mandrel by releasing the clutch in response to a torque threshold.
The foregoing summary is not intended to summarize each potential embodiment or every aspect of the present disclosure.
Briefly, the rig floor 14 has an opening 15 through which a tubing string 62 (such as drillpipe or casing) extends downwardly through a BOP and into a wellbore (not shown). The rail 20 extends from the rig floor 14 toward the crown block 16, and the traveling block 17 is supported by wire rope 19 connected to the crown block 16. The wire rope 19 is wound through sheaves of the crown block 16 and extends to drawworks 18 used for reeling (raising or lowering) the traveling block 17 relative to the derrick 10.
As noted, the top drive 30 has a non-rotating frame that includes the motor 32, the gearbox 34, an inlet 36, a swivel 38, the quill 40, and the like. The frame is supported on a trolley 22, which can ride along the rail 20 so the top drive 30 can move vertically with the traveling block 17 of the rig hoist.
The top drive 30 is used for handling tubulars 60, such as on a stand 61, so the stand 61 can be connected to the tubular string 62. In particular, the top drive motor 32, which can be electric or hydraulic, is operable to torsionally drive the quill 40, which can also be referred to as a main shaft or a drive stem. For example, the motor 32 can drive rotation of the quill 40 through the gearbox 34 or can drive the quill 40 directly without a gearbox. The quill 40 extends downwardly through other components of the top drive 30, and the flowback tool 100 is longitudinally and torsionally connected to the quill 40, such as by a threaded connection.
The swivel 38 supports rotation of the quill 40 relative to the top drive's frame. For example, the swivel 38 provides fluid communication between the non-rotating Kelly hose connection and the rotating quill 40 of the motor 32 for communicating fluid through the top drive 30. The swivel 38 also connects to the traveling block 17 for transferring the weight of the top drive 30 from the rotating quill 40 to the non-rotating traveling bock 17. The inlet 36 connects to a Kelly hose (not shown) and provides fluid communication between the Kelly hose and a bore of the quill 40. Finally, the quill 40 has a coupling, such as a threaded pin, formed at a lower end thereof connected to the flowback tool 100.
The pipe handler 50 has an elevator 54 that extends with bails 52 from the top drive 30 and is used for handling the tubulars 60. For example, each bail 52 is supported on a lifting lug of the top drive's frame, and each bail 52 connects to a respective lifting lug of the elevator 54. A link tilt can also be provided for swinging the elevator 54 relative to the top drive frame.
In operation, the pipe handler 50 engages the stand 61 and delivers the stand 61 to the tubing string 62 where the stand 61 can then be assembled therewith to extend the tubing string 62 during operations. To do this, the elevator 54 can be manually opened and closed on the tubular 60 of the stand 61, or the pipe handler 50 can include an actuator (not shown) for opening and closing the elevator 54. In general, the elevator 54 can include a bushing having a profile, such as a bottleneck, that is complementary to an upset formed on an end of the tubular. Alternatively, the elevator 54 may have a gripper, such as slips and a cone, capable of engaging an outer surface of the tubular 60 at any location therealong.
When closed on the tubular, the elevator 54 supports the tubular 60 for hoisting the stand 61 of preassembled joints. (In the present discussion and those that follow, the tubular 60 is shown and discussed as drillpipe, but it will be understood that other forms of tubulars can be used, such as casing.)
When the top drive 30 manipulates the stand 61, the flowback tool 100 can interface with the end 64 of the tubular 60 in a fluid connection and in a mechanical connection as discussed below. In particular, the flowback tool 100 supported on the top drive 30 is a fully mechanical tool that can be controlled by a driller using the rotation imparted by the top drive 30 via the motor 32 and quill 40. When operated, the flowback tool 100 can connect to the end 64 of the tubular 60 in a fluid connection so fluid communication can be made with the tubular 60. For example, with the elevator 54 supporting the tubular 60 below the top drive 30, the quill 40 can be rotated to establish a fluid connection between the flowback tool 100 and the upper end of the tubular 60.
Additionally, the flowback tool 100 can also connect to the end 64 of the tubular 60 in a mechanical connection so that, in addition to the fluid communication, the weight of the tubular 60, stand 61, and the like can be supported by the tool 100 and rotation can be imparted thereto with the rotation of the quill 40. For example, the quill 40 is rotated to thread a portion of the flowback tool 100 to the tubular's end (i.e., box connection) 64. Threading the tubular 60 onto an intermediate component, such as the flowback tool 100 connected to the quill 40, can reduce wear on the threaded end of the quill 40. Once connected to the quill 40, the tubulars 60 on the stand 61 can be added to a tubing string 62 held at the rig floor 14 by lowering the tubing stand 61 and threading it into the rest of the tubing string 62.
The mandrel 120 has a flow passage therethrough having a valve 130, which is a mud saver valve as discussed below. An annular seal 150 on the end of the barrel 140 is configured to sealably engage with the tubular 60. For example, the annular seal 150 can sealingly engage an outer surface of the tubular 60 at its box connection 64, thereby providing fluid communication between the top drive (30) and the bore of the tubular 60. Additionally, a coupling or cross-over 124b on the mandrel 120 is configured to removably thread to the box connection 64 of the tubular 60. This may be done so a mechanical connection can be made, such as when a well control operation needs to be performed or when the weight of a tubing string needs to be supported.
For its part, the clutch 160 has a torque interface between the clutch's components, as discussed in more detail below. For example, one portion of the clutch 160 is fixed on the barrel 140 of the mechanical stroke tool 110. Another portion of the clutch 160 includes an anti-rotation arm 192, which can have disengaged and engaged conditions with a portion of the top drive (30). In particular, the anti-rotation arm 192 on the clutch 160 can contact a bail 52 of the top drive (30) to allow extension/retraction of the mechanical stroke barrel 140. The driller can use visual indicators 53a-b on the bails 52 for determining the extended/retracted positions of the mechanical stroke's barrel 140, and the clutch 160 can avoid damage to the flowback tool 100 when overextending/retracting the stroke barrel 140.
During operations, the outer barrel 140 of the mechanical stroke tool 110 can be moved by a cam/threaded engagement as the mandrel 120 is rotated. The barrel 140, when prevented from rotating with the mandrel 120 by engagement of the clutch 160 with the bail 52, can thereby move in a stroke direction along the axis. The annular seal 150 on the distal end of the barrel 140 can then sealably engage with the tubular 60, such as shown in
The driller can use the alignment of the arm 192 with the visual indicators 53a-b of the bail 52 when controlling the extension/retraction of the barrel 140 with the rotation of the mandrel 120 by the top drive 30. When the torque threshold of the clutch 160 is reached, the second portion of the clutch 160 having the arm 192 can slip relative to the clutch's first portion fixed to the barrel 140. At this point, the clutch 160 can allow the barrel 140 to rotate with the rotation of the mandrel 120, except that a certain amount of friction of the annular seal 150 engaged with the tubular 60 may hinder the cylinder's rotation. In the meantime, the coupling 124b of the mandrel 120 can be threaded with the box connection 64 of the tubular 60. Establishing this threaded connection can be used for well control operations so that fluid communication can be established between the mandrel 120 and tubular 60. Additionally, establishing this threaded connection can be used when the weight of the tubular 60 (and any connected tubing stand or string) is to be held by the top drive (30).
Turning now to more details of the flowback tool 100,
As noted previously, the flowback tool 100 includes a mechanical stroke tool 110 having an inner body or mandrel 120 disposed in an outer body, cylinder, or barrel 140. Also, the flowback tool 100 includes a clutch 160 mounted on the barrel 140.
Looking first at the mandrel 120, a flow passage 122 in the mandrel 120 communicates a connection 124a at one end of the mandrel 120 to a coupling 124b at the other end of the mandrel 120. The connection 124a can be integrated into the mandrel 120 so that the mandrel 120 includes an integrated box connection. Alternatively and as shown here, the connection 124a is a top crossover connected to a top end of the mandrel 120. The top crossover 124a has a box connection for connection to the quill 40 of the top drive (30). A collar 126a can engage with splines on the top crossover 124a and the mandrel's top end to prevent rotation of the crossover 124.
The coupling 124b on the other end of the mandrel 120 can also be a crossover connected to the bottom end of the mandrel 120. This bottom crossover 124b includes a pin connection. In a similar fashion as before, a collar 126b can engage with splines on the bottom coupling 124b and the mandrel's bottom end to prevent rotation. In an alternative arrangement, features of the bottom crossover 124b can be an integral component of the mandrel 120 so that the mandrel 120 includes an integrated pin connection. However, it is preferable that the bottom crossover 124b be a replaceable coupling.
The mandrel 120 has a cam engagement with the barrel 140. For example, the outer surface of the mandrel 120 and an inner surface 142 of the barrel 140 can have engaged thread, such as a stub-Acme thread. In operation, rotation in the CW direction retracts the barrel 140, while rotation in the CCW direction extends the barrel 140. As long as the barrel 140 is prevented from rotating, clockwise rotation of the mandrel 120 will move the barrel 140 in one stroke direction, while counterclockwise rotation of the mandrel 120 will move the barrel 140 in the opposite direction. Toward the mandrel's bottom end, the mandrel 120 includes a carrier 128 with seals and a backup stopper for sealing inside the barrel 140.
The bottom end of the barrel 140 has the annular seal 150, which includes a top ring 152, a lip ring 154, a conical seal element 156, and a stop ring 158. The top ring 152 threads onto the barrel 140. The stop ring 158 fits against a wedge shoulder of the top ring 152, and the conical seal 156 fits against an edge of the stop ring 158. Finally, the lip ring 154 threads onto the top ring 152 to hold the stop ring 158 and the seal 156 captive. An outer locking ring 155 having splined engagement can prevent rotation of these components.
The clutch 160 is disposed toward the top end of the barrel 140. In general, the clutch 160 has first and second portions, which define an interface with a torque threshold between them. The first portion generally includes a housing 162 that is fixed on the barrel 140 of the mechanical stroke tool 100. For example, the housing 162 can engage splines and shoulders on the outer surface of the barrel 140. The second portion generally includes a slip ring 180 and a collar 190 disposed on a slip ring 180.
The interface with the torque threshold between these portions (162 & 180, 190) includes brake pads or rings 166a-b and one or more biasing elements 170 engaged between surfaces 164a-b of the housing 162 and surfaces 186a-b of the slip ring 180. Finally, the collar 190 has the anti-rotation arm 192, which can contact a bail to allow extension/retraction of the barrel 140 in a mechanical stroke as noted above. The arm 192 can have an extended condition as shown in which the arm 192 projects radially outward. The arm 192 can also be moved to a retracted condition in which the arm 192 projects downward and will not contact a bail during rotation.
As further shown, the flowback tool 100 includes a mud saver valve 130 disposed internally in the flow bore 122 of the mandrel 120. The mud saver valve 130 can be self-actuated and can be installed in one step as a pre-assembled cartridge into the mandrel's bore 122.
Details of the mud saver valve 130 can be similar to those disclosed in U.S. Pat. Nos. 8,118,106 and 8,141,642, which are incorporated herein by reference. As shown in the detail of
In a fill or circulation condition, for example, fluid communicated down through the mandrel's bore 122 passes through the baffle 136 and acts against the seat 137, which is biased by the seat spring 138. When the fluid pressure or flow differential overcomes the bias of the seat spring 138, the seat 137 moves away from the poppet 133, which remains extended downhole by the spring 135 on the stem 134. At this point, the fluid for filing or circulating can flow past the mud saver valve 130 and out of the bottom crossover 124b of the mandrel 120.
In a reverse flow condition, returns coming up through the mandrel's bore 122 act against the poppet 133, which is biased by the spring 135 on the stem 134. When the fluid pressure or flow differential overcomes the bias of the spring 135, the poppet 133 moves away from the seat 137, which remains shouldered by the body 131 and the cap 132. At this point, the returns can flow up through the mud saver valve 130 and out of the top crossover 124a of the mandrel 120. When there is low fluid pressure in either direction, the mud saver valve 130 closes.
Operation of the flowback tool 100 of
Depending on the stage of rig operations, the fluid communication through the flowback tool 100 can allow the tubular 60 to be filled with drilling fluid, can allow for circulation of drilling fluid through the tubular 60 during advancement of the tubular 60 into the wellbore, and/or can allow any returns displaced during advancement of the tubular into the wellbore to flow up through the flowback tool 100 when the string is lowered into the wellbore.
As generally noted above, the fluid communication is first achieved by partially extending the barrel 140 with the rotation of the top drive (30) so that the annular seal 150 of the barrel 140 seals on the outer diameter of the tubular 60. The driller extends the barrel 140 until the anti-rotation arm 192 reaches the bail marking (53a-b). As shown in more detail in
In addition to the fluid connection, a mechanical connection of the flowback tool 100 can be made with the tubular 60 during operations. For example, the stand (61) having tubular 60 may be ready to be made up with a tubing string (62) on the rig (10) so the tubing string (62) can then be advanced into the wellbore. The mechanical connection may be made during well control operations or when the weight of the tubing string is to be supported. The load rating for the mechanical connection can be up to 1500 tons (depending on connection size and grade selected).
One of the occasions where it may be required to apply torque on the rotation higher than the brake torque for the clutch 160 is during a well control situation. Another occasion is when the weight of the tubing string (62) is to be supported. For well control, for example, it is necessary to make up the flowback tool 100 to the tubular's box connection 64 via the threads on the mandrel's bottom crossover 124b. Accordingly, the mechanical connection can be used to handle a well control event, such as a kick or underbalanced pressure situation, or to support string weight.
In the mechanical connection as shown in
As schematically shown in
With the additional sealing afforded by the threaded connection between the coupling 124b and the box connection 64 as shown in
During the fluid and mechanical connection, the tubular 60 may then be advanced into the wellbore until another tubular (joint or stand) needs to be added. Further, the mechanical connection allows for the tubular 60 to be rotated while being advanced.
As shown in
The clutch's housing 162 is mounted on the mechanical stroke barrel 140 that moves axially (up or down) by the action of the top drive's quill rotation. The barrel 140 has a predefined travel or stroke on the mandrel 120. The mandrel 120 has an external thread (stub-acme or similar), and the barrel 140 has an internal thread that engages with the mandrel 120. The mandrel 120 is connected to the top drive's quill 40 using a threaded connection 124a. When the top drive's quill 40 rotates, then the mandrel 120 rotates with it as one component. When the rotation arm 192 is extended and contacts the top drive's bail (52), the barrel 140 will start moving up or down depending on the direction of the quill's rotation (CW or CCW).
Once the driller reaches the end of the stroke of the barrel 140 by rotating the quill 40, the barrel 140 will hit a stop where it cannot move further up or down (depending on the direction). The slip ring 180 will slip in the rotational direction inside the clutch 160 once the brake force in the pads 166a-b has been reached. At this point, the mandrel 120 and the barrel 140 will rotate together but without any axial movement from the barrel 140. This will prevent any damage to the internal and external threads on the barrel 140 and mandrel 120 respectively.
As noted in the Background of the present disclosure, existing designs rely on the driller watching the visual indicators 53a-b to stop the quill's rotation once the maximum and minimum stroke positions have been reached. The existing designs do not provide any safety mechanism to prevent damage to the mechanical stroke tool 110 when the quill 40 is over-rotated by the driller. However, the clutch 160 disclosed herein allows the driller to over-rotate the quill 40 without causing any damage to the mechanical stroke tool 110. The clutch 160 allows rotation of the arm 192 when torque on the top drive (30) is exceeded to screw in the mandrel's bottom coupling 124a with the tubular 60, which can be done to perform well control operators or to hold the weight of the tubular 60 as already noted.
In general and as discussed in more detail below, the clutch 160 can have a wet design or a dry design. In the wet design, the internal components are submerged in oil. This wet design allows temperatures to be kept low when the slip ring 180 slips with respect to the brakes 166a-b. Also, the wet design of the clutch 160 can reduce noise and prolong wear in the brakes 166a-b. The dry design does not use oil in the clutch 160. The dry design clutch can provide a better friction coefficient with less preload on the biasing element 170 considering that there is no oil in contact with the brakes 166a-b.
Having an understanding of how the clutch 160 operates, further details of the clutch 160 are now described.
In this embodiment, the clutch 160 uses Belleville springs 172 for the biasing elements. The housing 160 has a lower internal shoulder 164a and an upper internal shoulder 164b. (For assembly purposes, the housing 162 can have two housing portions 163a-b that couple together.) Locking tabs 165 on the inner lower end of the housing 162 can engage splines of the barrel (140), as shown in
Inside the housing 162, the push ring 161a is supported on the lower internal shoulder 164a, and the Belleville springs 172 are stacked inside the housing 162 on the push ring 161a. The lower brake pad 166a fits inside the housing 162 and is biased by the stacked Belleville springs 172 away from the lower internal shoulder 164a. The slip ring 180 fits in the housing 162, and a brass bushing 168 can fit inside the slip ring 180.
The slip ring 180 has a lower surface 186a engaged by the lower brake pad 166a. The upper brake pad 166b fits on the slip ring 180 and engages an upper surface 186b of the slip ring 180. The upper inner shoulder 164b of the housing 162 (i.e., the upper housing portion 163a) then fits against the upper brake pad 164b. Adjustment screws 161b at the bottom of the housing 162 can be adjusted to move the push ring 161a and can change the bias of the springs 172. A preload is applied to the Belleville springs 172 by rotating the adjustment screws 161b that push the plate 161a upward to increase the force acting on the brakes 166a-b. In turn, the brakes 166a-b (upper and lower) compress against the slip ring 180 attached to the rotation collar 190 and arm 192, thereby making it harder to rotate around the axis unless the torque applied overcomes the brake torque created by the brakes 166a-b and the preload of the springs 172.
The upper and lower brake pads 166a-b, as best shown in
Finally as shown in
As the barrel (140) rotates on which the clutch 160 is held, the housing 162 rotates, as do the brake pads 166a-b. The anti-rotation arm 192, although it may originally rotate, engages against a bail (52), which prevents its further rotation. As a result, the slip ring 180 connected by the splines 182 to the collar 190 for the anti-rotation arm 192 stops turning with the rotation of the barrel (140) and housing 162. Instead, the opposing brake pads 166a-b biased against the upper and lower surfaces 186a-b of the slip ring 180 ride against them, and the friction acts against the rotation of the cylinder (140) and housing 162. Depending on the bias and the friction, the barrel (140) can be torqued an amount against the clutch 160 so that rotation of the barrel (140) by the top drive (30) can be stopped.
This arrangement is similar to that disclosed above with reference to
In the third embodiment, the clutch 160 again uses compression springs 174, but other biasing elements can be used. This arrangement is similar to that disclosed above with reference to
In the fourth embodiment, the clutch 160 gain uses compression springs 174, but other biasing elements can be used. The compression springs 174 are arranged between the push ring 161a and the stack plates 184a-b, and they work under the same basic principle as the previous embodiments. As shown, however, the clutch 160 uses a set of alternating stack plates 184a-b that create part of the brake force for this application.
The stack plates 184a-b can be composed of the same or different materials. For example, the stack plates 184a of
In addition to adjusting the push ring 161a with the adjustment screws 161b to change the bias of the compression springs 174, the clutch 160 can also be adjusted by adding more sets of steel plates 184a and brake discs 184b in the assembly. This capability expands the adjustment range for the clutch 160 by selecting multiple combinations and added flexibility by using the adjustment screws to vary the brake force as well.
As before, the internal members of the clutch 160 can be submerged in oil to reduce heat and noise when the brake force is overcome by the rotation of the top drive quill. Seals 169a-b are included to create a clutch cavity for the oil. A port is provided to fill the clutch cavity with oil, and the oil can be drained by removing one or more adjustment screws 161b. (As will be appreciated, the arrangement of the clutch 160 in
The slip ring 180 in
During operations, the compression springs 174 compress the plates 184a and the brake discs 184b creating a high friction force (brake torque). There will be relative angular movement between the brake discs 184b and the steel plates 184a only when the torque applied to the rotation arm 192, collar 190, and slip ring 180 is higher than the brake torque created by the clutch 160.
As shown in
For its part, the rotating brake ring 190′ has upper and lower brake pads 196a-b (
As best shown in
Thus, as described above, the slip ring 180 is mechanically connected to the outer housing 162. In particular, the slip ring 180 has the external spline profiles 189a in which the splines 167c of the outer housing 162 engage to prevent rotation between these components. The slip ring 180 is also mechanically connected to the support pate 161c by the set of screws 161d located on the bottom of the safety clutch 160. Moreover, the slip ring 180 is mechanically connected to the barrel (140) by torque parallel keys (189c;
Again, the purpose of the safety clutch 160 in this application is to prevent any damage to the thread between the mandrel (120) and the barrel (140) when the top drive quill is over-rotated in the CW or CCW direction. The basic principle of the safety clutch 160 relies on a preload applied to the Belleville springs 176 by rotating the adjustment screws 161e that push the outer housing 162 to increase the force acting on the brake pads 196a-b mounted on the rotating brake ring 190′ connected to the anti-rotation arm 192. The upper and lower brake pads 196a-b create a friction force between the outer housing 162 and the slip ring 180, making it difficult to create a relative rotational movement of the rotating brake ring 190′ and anti-rotation arm 192 unless the torque limit is reached or exceeded by the torque created by the top drive quill.
One of the only occasions where it may be required to apply a torque on the rotation arm 192 higher than the brake torque includes a well control situation when it is necessary to make up the mandrel's coupling (124b) to the drillpipe's connection (64) via threads. This is achieved by fully retracting the barrel (140) in CW rotation. The barrel (140) then hits a stop where it is not possible to retract anymore. At this point, the top drive quill will continue rotation in the CW direction. The torque applied to the rotation arm 192 will overcome the brake torque in the clutch 160, and then the mandrel's coupling (124b) can be screwed into the drillpipe's connection (64) without damaging the stub-acme threads on the mandrel (120) and the barrel (140) because the barrel (140) can essentially rotate with the turning of the mandrel (120).
The foregoing description of preferred and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concepts conceived of by the Applicants. It will be appreciated with the benefit of the present disclosure that features described above in accordance with any embodiment or aspect of the disclosed subject matter can be utilized, either alone or in combination, with any other described feature, in any other embodiment or aspect of the disclosed subject matter.
In exchange for disclosing the inventive concepts contained herein, the Applicants desire all patent rights afforded by the appended claims. Therefore, it is intended that the appended claims include all modifications and alterations to the full extent that they come within the scope of the following claims or the equivalents thereof.