SYSTEM AND METHOD

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to and the benefit of U.S. Provisional Application No. 62/329,889, entitled "TOP DRIVE POWERED DIFFERENTIAL SPEED ROTATION SYSTEM AND METHOD," filed April 29, 2016, which is hereby incorporated by reference in its entirety.

BACKGROUND

[0002] Embodiments of the present disclosure relate generally to the field of drilling and processing of wells. More particularly, present embodiments relate to a system and method for connecting or disconnecting lengths of tubular.

[0003] Top drives are typically utilized in well drilling and maintenance operations, such as operations related to oil and gas exploration. In conventional oil and gas operations, a well is typically drilled to a desired depth with a drill string, which includes drill pipe and a drilling bottom hole assembly (BHA). During a drilling process, the drill string may be supported and hoisted about a drilling rig by a hoisting system for eventual positioning down hole in a well. As the drill string is lowered into the well, a top drive system may rotate the drill string to facilitate drilling. The drill string may include multiple lengths of tubular that are coupled to one another by threaded connections or joints. In traditional operations, the lengths of tubular are coupled together and decoupled from one another using hydraulic tongs.

BRIEF DESCRIPTION

[0004] In a first embodiment, a system includes a first clamping mechanism configured to couple to a first tubular, wherein the first clamping mechanism comprises a first opening extending from a first outer circumference of the first clamping mechanism to a first central passage of the first clamping mechanism, a second clamping mechanism configured to couple to a second tubular, wherein the second clamping mechanism comprises a second opening extending from a second outer circumference of the second clamping mechanism to a second central passage of the second clamping mechanism, and a coupling mechanism coupling the first and second clamping mechanism, wherein the coupling mechanism comprises a gear assembly having a speed ratio greater than 1.

[0005] In a second embodiment, a method includes radially receiving a first tubular and a second tubular with a joint rotation system, rotating the first tubular at a first angular velocity in a radial direction with a top drive such that a first clamping mechanism of the joint rotation system coupled to the first tubular is rotated, rotating a first sprocket of the joint rotation system, the first sprocket engaged with the first clamping mechanism and configured to rotate as a result of rotating of the first clamping mechanism, rotating a second sprocket of the joint rotation system, the second sprocket fixedly coupled with the first sprocket and configured to rotate as a result of rotating of the first sprocket, rotating a second clamping mechanism of the joint rotation system, the second clamping mechanism engaged with the second sprocket and configured to rotate as a result of rotating the second sprocket, and rotating the second tubular at a second angular velocity in the radial direction, the second angular velocity being different from the first angular velocity, wherein the second tubular is rotated by the second clamping mechanism of the joint rotation system via coupling of the second clamping mechanism with the second tubular,

[0006] In a third embodiment, a system includes a joint rotation system. The joint rotation system includes a housing, a first clamping mechanism configured to clamp to a first pipe, wherein the first clamping mechanism comprises a first open mouth sprocket, a second clamping mechanism configured to clamp to a second pipe, wherein the second clamping mechanism comprises a second open mouth sprocket and wherein the first and second pipes are coupled by a threaded connection, a first chain-driven sprocket configured to be driven by rotation of the first clamping mechanism, and a second chain- driven sprocket fixed to the first chain-driven sprocket, wherein a speed ratio of the first and second chain-driven sprockets is greater than one, and the second chain-driven sprocket is configured to drive rotation of the second clamping mechanism, wherein the housing supports the first clamping mechanism, the second clamping mechanism, the first chain-driven sprocket, and the second-chain driven sprocket.

DRAWINGS

[0007] These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[0008] FIG. 1 is a schematic of a drilling rig, illustrating a joint rotation system, in accordance with an embodiment of the present techniques;

[0009] FIG. 2 is a schematic of a portion of a drilling rig, illustrating a joint rotation system, in accordance with an embodiment of the present techniques;

[0010] FIG. 3 is an upper perspective view of a joint rotation system, in accordance with an embodiment of the present techniques;

[0011] FIG. 4 is a lower perspective view of a joint rotation system, in accordance with an embodiment of the present techniques;

[0012] FIG. 5 is a side view, taken within line 5-5 of FIG. 2, of a joint rotation system, in accordance with an embodiment of the present techniques;

[0013] FIG. 6 is a cross-sectional axial view, taken along line 6-6 of FIG. 5, of a joint rotation system, in accordance with an embodiment of the present techniques; [0014] FIG. 7 is a cross-sectional axial view, taken along line 6-6 of FIG. 5, of a joint rotation system, in accordance with an embodiment of the present techniques;

[0015] FIG. 8 is a cross-sectional axial view, taken along line 8-8 of FIG. 5, of a joint rotation system, in accordance with an embodiment of the present techniques;

[0016] FIG. 9 is a cross-sectional axial view, taken along line 8-8 of FIG. 5, of a joint rotation system, in accordance with an embodiment of the present techniques;

[0017] FIG. 10 is a top view of a joint rotation system, in accordance with an embodiment of the present techniques; and

[0018] FIG. 1 1 is a top view of a joint rotation system, in accordance with an embodiment of the present techniques.

DETAILED DESCRIPTION

[0019] Embodiments of the present disclosure are directed toward a joint rotation system to enable assembly and disassembly of lengths of tubular to and from one another on a drilling rig. For example, the joint rotation system may be used to thread and unthread sections of drill pipe to and from one another to assemble or disassemble a drill string. As described in detail below, the joint rotation system is geared to grip and rotate two lengths of tubular at different speeds while a top drive or other rotational system rotates one of the lengths of tubular. As the joint rotation system rotates the two lengths of tubular at different speeds, the relative rotations (e.g., differential speeds) of the two lengths of tubular enable engagement (e.g., threading) or disengagement (e.g., unthreading) of the lengths of tubular to or from one another. As discussed below, the joint rotation system includes two or more clamping mechanisms configured to clamp the two lengths of tubular to be threaded or unthreaded. Additionally, the clamping mechanisms may have openings (e.g., enclosable openings) that enable efficient coupling of the joint rotation system to the two lengths of tubular to be connected or disconnected from one another. In other words, the configuration of the clamping mechanisms discussed below enables the joint rotation system to be quickly and readily engaged and disengaged with lengths of tubular to be connected or disconnected from one another.

[0020] FIG. 1 is a schematic of a drilling rig 10 in the process of drilling a well in accordance with present techniques. The drilling rig 10 features an elevated rig floor 12 and a derrick 14 extending above the rig floor 12. A supply reel 16 supplies drilling line 18 to a crown block 20 and traveling block 22 configured to hoist various types of drilling equipment above the rig floor 12. The drilling line 18 is secured to a deadline tiedown anchor 24, and a drawworks 26 regulates the amount of drilling line 18 in use and, consequently, the height of the traveling block 22 at a given moment. Below the rig floor 12, a drill string 28 extends downward into a wellbore 30 and is held stationary with respect to the rig floor 12 by a rotary table 32 and slips 34. A portion of the drill string 28 extends above the rig floor 12, forming a stump 36 to which another length of tubular 38 may be added. During operation, a top drive 40, hoisted by the traveling block 22, may engage and position the tubular 38 above the wellbore 30. The top drive 40 may then lower the coupled tubular 38 into engagement with the stump 36 and rotate the tubular 38 such that it connects with the stump 36 and becomes part of the drill string 28. Specifically, the top drive 40 includes a quill 42 used to turn the tubular 38 or other drilling equipment. Also, during other phases of operation of the drilling rig 10, the top drive 40 may be utilized to disconnect and remove sections of the tubular 38 from the drill string 28, as is illustrated in FIG. 1.

[0021] The drill string 28 may include multiple sections or lengths of threaded tubular 38 that are threadably coupled together using techniques in accordance with present embodiments. It should be noted that present embodiments may be utilized with drill pipe, casing, or other types of tubular. After setting or landing the drill string 28 in place such that the male threads of one section (e.g., one or more lengths) of the tubular 38 and the female threads of another section of the tubular 38 are engaged, the two sections of the tubular 38 may be joined by rotating one section relative to the other section (e.g., in a clockwise direction) such that the threaded portions tighten together. Thus, the two sections of tubular 38 may be threadably joined. Furthermore, as the drill string 28 is removed from the wellbore 30, the sections or lengths of the tubular 38 may be detached by disengaging the corresponding male and female threads of the respective sections of the tubular 38 via relative rotation of the two sections in a direction opposite than used for coupling. In accordance with presently disclosed embodiments, a joint rotation system 50 may be used to decouple multiple lengths of the threaded tubular 38 as the drill string 28 is removed from the wellbore 30. More specifically, in the manner described below, the top drive 40 and the joint rotation system 50 are used to rotate two lengths of tubular 38 coupled to one another at different speeds such that the relative rotations result in disengagement of the two sections of the tubular 38. Indeed, the joint rotation system 50 is geared (or coupled together and driven at a ratio) to facilitate rotation of the two sections of tubular 38 at different speeds, thereby breaking or disconnecting the threaded coupling between the two sections of tubular 38. In some embodiments, the joint rotation system 50 may be employed in reverse to coupled separate lengths or sections of tubular.

[0022] It should be noted that the illustration of FIG. 1 is intentionally simplified to focus on the top drive 40 and the joint rotation system 50. Many other components and tools may be employed during the various periods of formation and preparation of the well. Similarly, as will be appreciated by those skilled in the art, the orientation and environment of the well may vary widely depending upon the location and situation of the formations of interest. For example, rather than a generally vertical bore, the well, in practice, may include one or more deviations, including angled and horizontal runs. Similarly, while shown as a surface (land-based) operation, the well may be formed in water of vari ous depths, in which case the topside equipment may include an anchored or floating platform.

[0023] FIG. 2 is a simplified schematic of a portion of the drilling rig 10, illustrating the joint rotation system 50 for use in coupling, joining, breaking, or disconnecting threaded couplings between sections or lengths of tubular 38. In this illustrated embodiment, the drill string 28 is in the process of being removed from the wellbore 30. Specifically, multiple lengths of tubular 38, which are threadably connected to one another at tubular connections 52, are bemg removed from the wellbore 30. As such, the multiple sections or lengths of tubular 38 are rotated in the same direction but at different speeds relative to one another using the top drive 40 and the joint rotation system 50 in order to disconnect the tubular connections 52. Due to the different speeds of rotation, when disconnecting two sections or lengths of tubular 38, one length of tubular 38 may essentially be rotated counter-clockwise (e.g., in a direction opposite a direction 54) relative a second length of tubular 38, thereby disconnecting the tubular connection 52 of the two lengths of tubular 38. In other words, although both lengths of tubular 38 are bemg rotated in the same direction, because one is being rotated faster than the other, the length rotating faster is rotating in the direction 54 relative to the length being rotated slower.

[0024] When the drill string 28 is removed from the wellbore 30, it may be desirable to disconnect sections of tubular 38 that include multiple lengths of tubular. In other words, several lengths of tubular 38 may be left connected by the tubular connections 52 when the drill string 28 is removed from the wellbore 30 in sections (e.g., lengths of tubular 38 that are left connected to one another after removal from the wellbore 30 and drill string 28). For example, it may be desirable to remove sections of tubular 38 that each includes two or three lengths of tubular 38 that remain coupled together and thus limit trip times. The length of each section of tubular 38 kept intact (not decoupled at evety tubular connection 52) may be limited by the rig height. For example, when removing the drill string 28 from the wellbore 30, every second, third, or fourth tubular connection 52 may be broken or disconnected depending on individual tubular 38 lengths and the height of the drilling rig 10. In this manner, sections of tubular 38 including multiple tubular connections 52 that remain connected may be set aside for later use with the drilling rig 10. As will be appreciated, this practice may result in faster re-assembly of the drill string 28, when the drill string 28 is assembled for use within the wellbore 30 at a later time. [0025] To enable the disassembly of certain tubular connections 52 when the drill string 28 is removed from the wellbore 30, the joint rotation system 50 may be used. As mentioned above, the joint rotation system 50 is geared (or coupled together or driven at a ratio greater than one) to rotate two sections or lengths of tubular 38 at different speeds while the top drive 40 provides the motive force. Three lengths of tubular 38 are shown in FIG. 2 (e.g., a first length of tubular 56, a second length of tubular 58, and a third length of tubular 60). Additionally, the first and second lengths of tubular 56 and 58 are joined by a first threaded connection 62 (e.g., a tubular connection), and the second and third lengths 58 and 60 are joined by a second threaded connection 64 (e.g., a tubular connection).

[0026] In the illustrated embodiment, the joint rotation system 50 is positioned to disconnect the second threaded connection 64 as the three lengths 56, 58, and 60 of tubular 38 are rotated by the top drive 40, while maintaining the connection of the first threaded connection 62. In particular, as the top drive 40 rotates the three lengths 56, 58, and 60 of tubular 38 in the clockwise direction 54, the joint rotation system 50 creates a rotating speed differential between the second and third lengths 58 and 60 of tubular, thereby breaking or disconnecting the second threaded connection 64. Specifically, as the three lengths 56, 58, and 60 of tubular 38 are rotated in the clockwise direction 54, the joint rotation system 50 increases the rotational torque applied by the top drive 40 and applies the increased torque to the third length 60 of tubular 38. In this manner, the third length 60 of tubular 38 rotates in the clockwise direction 54 faster than the second length 58 of tubular 38 rotates in the clockwise direction 54, thereby unthreading the second threaded connection 64 and decoupling the second and third lengths 58 and 60 of tubular 38. Furthermore, as the first and second lengths 56 and 58 of tubular 38 are both rotated in the clockwise direction 54 and at the same speed, the first threaded connection 62 may not be at risk of becoming disconnected or unthreaded.

[0027] As mentioned above, present embodiments of the joint rotation system 50 include clamping mechanisms, each of which is configured to grip one of the lengths of tubular 38 of the drill string 28. For example, in the illustrated embodiment, the joint rotation system 50 may have a first clamping mechanism configured to grip the second length 58 of tubular 38 and a second clamping mechanism configured grip the third length 60 of tubular 38. As described in detail below, each clamping mechanism may have an opening (e.g., an enclosable opening) that enables efficient and engagement and disengagement of the joint rotation system 50 to and from the drill string 28. For example, the openings of the clamping mechanisms may be open to receive the second and third lengths 58 and 60 of tubular 38 when the joint rotation system 50 is coupled to the drill string 28. In certain embodiments, the clamping mechanisms may have a clasp or latch that encloses the openings once the joint rotation system 50 is positioned about the drill string 28. Thereafter, the joint rotation system 50 may be used to unthread the second length 58 of tubular 38 from the third length 60 of tubular 38. Once the tubular connection 50 is broken (e.g., unthreaded), the clamping mechanisms may be reopened, and the joint rotation system 50 may be readily removed from the drill string 28 for later use. In the illustrated embodiment, the joint rotation system 50 is supported by an exterior lifting frame 66, which may enable efficient and ergonomic placement of the joint rotation system 50 about and/or away from the drill string 28 when desired. For example, the exterior lifting frame 66 may include linkages, tracks, bars, hinges, pulleys, and/or other components to enable manipulation of the joint rotation system 50 toward and away from the drill string 28.

[0028] FIGS. 3 and 4 are perspective views of an embodiment of the joint rotation system 50. In the illustrated embodiment, joint rotation system 50 includes a first clamping mechanism 100 and a second clamping mechanism 102, which are coupled together by a gear assembly 104 (e.g., a sprocket assembly). While the illustrated embodiment describes the gear assembly 104, other embodiments may have any coupling assembly that couples (e.g., mechanically couples) the first clamping mechanism 100 and the second clamping mechanism 102 (e.g., at a drive ratio greater than one). A housing or outer frame 106 of the joint rotation system 50 supports the first clamping mechanism 100, the second clamping mechanism 102, and the gear assembly 104. The first and second clamping mechanisms 100 and 102 are configured to fixedly couple to respective lengths of tubular 38 that are joined to one another by the tubular connection 52 (e.g., a threaded connection). For example, the first clamping mechanism 100 may fixedly couple to the second length 58 of tubular 38 shown in FIG. 2, and the second clamping mechanism 102 may couple to the third length 60 of tubular 38 shown in FIG. 2. In other words, the first clamping mechanism 100 couples to the top tubular 38 of the tubular connection 52, and the second clamping mechanism 102 couples to the bottom tubular 38 of the tubular connection 52. As such, the joint rotation system 50 would operate to disengage the second threaded connection 64 shown in FIG. 2.

[0029] The clamping mechanisms 100 and 102 may include various grips, braces, or other systems configured to secure the joint rotation system 50 to the joints of tubular 38. For example, in the illustrated embodiment, the clamping mechanisms 100 and 102 include hydraulic cylinders 108. The clamping mechanisms 100 and 102 may each have a plurality of hydraulic cylinders 108 disposed about a central passage 110 of the joint rotation system 50 through which the lengths of tubular 38 may extend when the joint rotation system 50 is disposed about the drill string 28. The illustrated embodiment shows a first hydraulic cylinder 112 of the first clamping mechanism 100 and a second hydraulic cylinder 114 of the second clamping mechanism 102. The hydraulic cylinders 108 are configured to actuate radially inward (e.g., relative to a central axis of the drill string 28) to grip one of the lengths of tubular 38. As such, each of the first and second clamping mechanism 100 and 102 may have 2, 3, 4, 5, or more hydraulic cylinders 108 disposed about the central passage 1 10 to cooperatively grip the respective tubular 38.

[0030] As will be appreciated, in embodiments where the clamping mechanisms 00 and 102 include hydraulic cylinders 108, hydraulics hoses may be run to the joint rotation system 50 to enable actuation of the hydraulic cylinders 108 with hydraulic fluid. As shown in FIG. 5, the housing 106 of the joint rotation system 50 may include flanges 116 or other structural features (hooks, coil drums, etc.) that may enable and/or improve spatial management of the hydraulic hoses. In other embodiments, the clamping mechanism 100 and 102 may include other actuation or gripping mechanisms that are actuated pneumatically, electrically, magnetically, and so forth. In such embodiments, the flanges 1 16 may be used to similarly manage hoses, cables, wires (e.g., communication or feedback wires), or other tubes that are run to the joint rotation system 50.

[0031] Referring back to FIGS. 3 and 4, each of the first and second clamping mechanisms 100 and 102 also includes one or more open mouth sprockets 118. For example, in the illustrated embodiment, the first clamping mechanism 100 has a first plurality 120 of open mouth sprockets 1 18, and the second clamping mechanism 102 has a second plurality 122 of open mouth sprockets 118. The first and second pluralities 120 and 122 of open mouth sprockets 118 are axiaily separated by a divider plate 123, winch may be fixed to the housing 106. Each of the open mouth sprockets 1 18 includes a plurality of teeth 124 arrayed about an outer circumference 126 of the respective open mouth sprocket 118. In certain embodiments, the open mouth sprockets 118 of the first and second pluralities 120 and 122 may be approximately the same size and have approximately the same number of teeth 124. Additionally, each open mouth sprocket 118 includes an opening 128 extending from the respective outer circumference 126 of the open mouth sprocket 118 to the central passage 110 of the joint rotation system 50. Thus, when each of the open mouth sprockets 1 18 is similarly aligned or oriented, as shown in FIGS. 4 and 5, the joint rotation system 50 may quickly and efficiently be placed about the drill string 28. Indeed, the joint rotation system 50 may be quickly placed about the drill string 28, the first clamping mechanism 100 may be radially aligned with one tubular 38 coupled by the tubular connection 52 (e.g., the second length 58 of tubular 38 shown in FIG 2), and the second clamping mechanism 102 may be radially aligned with another tubular 38 coupled by the tubular connection 52 (e.g., the third length 60 of tubular 38 shown in FIG. 2). Thereafter, the respective hydraulic cylinders 108 may be actuated to grip the tubulars 38 coupled by the tubular connection 52. [0032] The first plurality 120 of open mouth sprockets 1 18 may be rotational ly fixed to one another. The first plurality 120 of open mouth sprockets 118 is also rotationally fixed to the hydraulic cylinders 108 of the first clamping mechanism 100 (e.g., first hydraulic cylinder 112). Similarly, the second plurality 122 of open mouth sprockets 1 18 may be rotationally fixed to one another, and the second plurality 122 of open mouth sprockets 118 is also rotationally fixed to the hydraulic cylinders 108 of the second clamping mechanism 102 (e.g., second hydraulic cylinder 114). Thus, when the first clamping mechanism 100 is coupled to one of the lengths of tubular 38 coupled via the tubular connection 52, rotational movement of the tubular 38 (e.g., driven by the top drive 40) will be transferred to the first plurality 120 of open mouth sprockets 118. In the manner described below, rotation of the first plurality 120 of open mouth sprockets 118 is transferred to the second plurality 122 of open mouth sprockets 118 via the gear assembly 104 (e.g., at a gear ratio greater than one). Thereafter, rotation of the second plurality 122 of open mouth sprockets 118 is transferred to the other length of tubular 38 coupled at the tubular connection 52 via the hydraulic cylinders 108 of the second clamping mechanism 102 (e.g., second hydraulic cylinder 1 14). As mentioned above, the gear ratio of the gear assembly 104 enables differential speed of rotation between the two tubulars 38 to enable disengagement of the tubular connection 52.

[0033] The gear assembly 104 contained within the housing 106 joins the first and second clamping mechanisms 100 and 102 (e.g., at a gear ratio greater than one). For example, the gear assembly 104 may be a sprocket assembly having sprockets, gears, chains, belts, and/or other components. The gear assembly 104 is configured to increase the rotational speed generated by the top drive 40 and apply the increased rotational speed to one of the lengths of tubular 38 (e.g., the lower of the two lengths of tubular 38) joined by the tubular connection 52. For example, the joint rotation system 50 is configured to increase the rotational speed of the third length 60 of tubular 38 shown in FIG. 2 relative to the rotational speed of the second length 58 of tubular 38 shown in FIG. 2, In this manner, the second threaded connection 64 would be broken, and the second and third lengths 58 and 60 would decouple from one another. [0034] In the illustrated embodiment, the gear assembly 104 (e.g., sprocket assembly) includes a top portion 130 and a bottom portion 132. The top portion 130 includes a first sprocket 134, a second sprocket 136 (e.g., an idler sprocket), and a third sprocket 138, which are drivingly coupled to one another by a first chain 140 (e.g., a multi-link chain). The bottom portion 132 of the gear assembly 104 includes a fourth sprocket 142 and a fifth sprocket 144, which are drivingly coupled to one another by a second chain 146 (e.g., a multi-link chain). In certain embodiments, one or more of the first, second, third, fourth, and fifth sprockets 134, 136, 138, 142, and 144 may include multiple sprockets (e.g., stacked on top of one another) to improve or increase transfer of rotational movement between the other respective sprockets in the top portion 130 or bottom portion 132 via the first and/or second chains 140 and 146. As discussed in detail below, the first sprocket 134 of the top portion 130 of the gear assembly 104 and the fourth sprocket 142 of the bottom portion 132 of the gear assembly 104 are rotationally fixed to one another at a gear ratio greater than one. For example, the first sprocket 134 and the forth sprocket 142 may be integrally formed as one piece, may be connected to one another by a rod, or otherwise rotationally fixed to one another. As such, the first sprocket 134 of the top portion 130 will rotate at the same speed as the fourt sprocket 142 of the bottom portion 132. However, the first sprocket 134 and the fourth sprocket 142 are not the same size (e.g. , same diameter). In particular, the first sprocket 134 is smaller (e.g., has fewer teeth) than the fourth sprocket 142.

[0035] To transfer rotational motion from the first clamping mechanism 100 to the second clamping mechanism 102, the top portion 130 of the gear assembly 104 engages with the first plurality 120 of open mouth sprockets 118, and the bottom portion 132 of the gear assembly 104 engages with the second plurality 122 of open mouth sprockets 118. Specifically, the first chain 140 of the top portion 130 engages with the teeth 124 of the first plurality 120 of open mouth sprockets 118. To enable this engagement, the first, second, and third sprockets 134, 136, and 138 are arranged (e.g., in a generally triangular arrangement) within the housing 106 such that the first chain 140 engages with a minimum portion (e.g. , minimum arc length) 150 of the circumference 126 of the first plurality 120 of open mouth sprockets 118, For example, the minimum portion 150 may he approximately 50 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, or more of the circumference 126 of the first plurality 120 of open mouth sprockets 118.

[0036] In the illustrated embodiment, the position of the third sprocket 138 is also adjustable to enable tension adjustment of the first chain 140 and/or an amount of contact between the first chain 140 and the first plurality 120 of open mouth sprockets 118. Specifically, the third sprocket 138 may be coupled to a threaded knob 152 that extends through a slot 154 formed in the housing 106. To adjust the position of the third sprocket 138 within the housing 106, and thus adjust the tension in the first chain 140, the threaded knob 152 may be loosened and translated or slid along the slot 154 to a position that provides a desired tension in the first chain 140. Thereafter, the threaded knob 152 may be tightened (e.g., against the housing 106) to hold the third sprocket 138 in the desired position. In some embodiments, the second sprocket 136 may additionally or alternatively be adjustable to enable adjustment of the tension in the first chain 140.

[0037] Similar to the first chain 140 and the first plurality 120 of open mouth sprockets 118, the second chain 146 of the bottom portion 132 engages with the second plurality 122 of open mouth sprockets 118. Specifically, the second chain 146 of the bottom portion 132 engages with the teeth 124 of the second plurality 122 of open mouth sprockets 118. The fourth and fifth sprockets 142 and 144 are also arranged within the housing 106 and the second chain 146 is sized such that the second chain 140 engages with a minimum portion (e.g., minimum arc length) 156 of the circumference 126 of the second plurality 122 of open mouth sprockets 118. For example, the minimum portion 160 may be approximately 50 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, or more of the circumference 126 of the second plurality 122 of open mouth sprockets 18. As similarly discussed above with respect to the top portion 130, the fifth sprocket 144 may also be position-adjustable to enable adjustment of tension in the second chain 146 of the bottom portion 132 (e.g., via a threaded knob extending through a slot in the housing 106) and/or to adjust an amount of contact between the second chain 146 and the second plurality 122 of open mouth sprockets 1 18. While the illustrated embodiment of the bottom portion 132 does not include an idler sprocket (e.g., an additional sprocket similar to the second sprocket 136 of the top portion 130), other embodiments of the gear assembly 104 may include an additional idler sprocket in the bottom portion 132, and the additional sprocket may also be adjustable to further enable tension adjustment of the second chain 46.

[0038] Furthermore, although the illustrated embodiment includes the first, second, third, fourth, and fifth sprockets 134, 136, 38, 142, and 144 of the gear assembly 04, other embodiments may include other or additional components. For example, the gear assembly 104 may include other sprockets, rollers, and so forth to enable adequate contact between the first and second chains 140 and 146 and the respective open mouth sprockets 1 18. Such components may also further enable tension adjustment of the of the first and second chains 140 and 146 to facilitate removal of the first and second chains 140 and 146 from the gear assembly 104 and/or to adjust a level or amount of contact between the first and second chains 140 and 146 and the respective open mouth sprockets 118.

[0039] As mentioned above, each of the open mouth sprockets 118 includes the opening 128 to enable efficient and ready positioning of the joint rotation system 50 about the drill string 28, but the embodiments shown in FIGS. 3 and 4 do not include any mechanism or feature to enable enclosure of the opening 128 in each sprocket 118. However, other embodiments of the joint rotation system 50 may include a mechanism or feature, such as a latch or clasp, which may be selectively positioned to enclose the opening 128 of each sprocket 1 18 (e.g., once the drill string 28 is positioned within the central passage 110 of the joint rotation system 50. Examples of such embodiments are discussed below with reference to FIGS. 6-11.

[0040] FIG. 5 is a side view of an embodiment of the joint rotation system 50, illustrating operation of the joint rotation system 50. Specifically, in the illustrated embodiment, the joint rotation system 50 is breaking or unthreading a threaded connection 180 (e.g., a connection between two lengths of tubular 38), which couples a first length 182 of tubular 38 (e.g., a top length) and a second length 184 of tubular 38 (e.g., a bottom length).

[0041] As will be appreciated by one skilled in the art, the torque applied to the first length 182 by the top drive 40 may be expressed as where A/B is the gear ratio between the first plurality 120 of open mouth sprockets 118 and the first sprocket 134, C/D is the gear ratio between the second plurality 122 of open mouth sprockets 118 and the fourth sprocket 142, Ttd is the torque acting on the first length 182 of tubular 38, Tds is the torque acting on the second length 184 of tubular 38 (e.g., the drill string 28), and Tj is the torque acting on the threaded connection 180. As mentioned above, the first and second pluralities 120 and 122 of open mouth sprockets 118 may be approximately the same size and have approximately the same number of teeth 124. Therefore, Equation (1) may be expressed as

[0042] When breaking or unthreading the threaded connection 180, the torque acting on the second length 184 (i.e., Tds) may be approximately 0 as frictional torque will arise once motion actually begins. As a result, the torque acting on the second length 184 (i.e., Tds) may not affect the top drive 40 output torque (i.e., Ttd) during the initial breaking or unthreading of the threaded connection 180. Consequently, Equation (2) reduces to [0043] Similarly, once the threaded connection 180 begins to unthread and the threaded connection 180 torque (i.e., Tj) disappears, the top drive 40 may only experience the frictional torque, which may be expressed by

[0044] As will be appreciated by one skilled in the art, D/B may be considered the overall drive or speed ratio of the gear assembly 104. Indeed, the drive or speed ratio may be greater than one, thereby enabling faster rotation of the second length 184 relative to the first length 182, which results in the unthreading of the threaded connection 180. For example, in certain embodiments the gear or speed ratio of the gear assembly 104 (e.g., between the first sprocket 134 and fourth sprocket 142) may be between approximately 5;4 and 2: 1.

[0045] In certain embodiments, the first and second clamping mechanisms 00 and 102 may be engaged with the first and second lengths 182 and 184, respectively to initially break the threaded connection 180 by rotating top drive 40 in a first direction. After the threaded connection 1 80 is partially broken (e.g., not completely unthreaded), the first clamping mechanism 100 may be disengaged from the first length 182 while leaving the second clamping mechanism 102 engaged with the second length 184. Then, the top drive 40 may be rotated in a second direction opposite the first direction to fully disengaged (e.g., unthread) the first length 182 from the second length 184.

[0046] FIGS. 6-1 1 illustrate an embodiment of the joint rotation system 50 having first and second clamping mechanisms 100 and 102 with enclosable openings. Specifically, the illustrated embodiments include first and second clamping mechanisms 100 and 102 having open mouth sprockets 1 1 8 where each open mouth sprocket 118 has a latch 200 (e.g., a hinged latch) that may be used to enclose the respective opening 128 of the open mouth sprocket 1 18. [0047] For example, FIG. 6 is a cross-sectional axial view of the joint rotation system 50, taken along line 6-6 of FIG. 5, illustrating one of the open mouth sprockets 118 of the first clamping mechanism 100. The open mouth sprocket 118 shown in FIG. 6 has the latch 200, which is pivotably connected to a mam portion 202 (e.g., a disk) of the open mouth sprocket 118. In the illustrated embodiment, the latch 200 is shown in an open position. The latch 200 includes a base portion 204 that is coupled to the main portion 202 of the open mouth sprocket 1 18. The base portion 204 may be pivotably coupled to the main portion 202 via a hinge, pin, or other mechanism that enables pivoting of the latch 200.

[0048] The latch 200 also includes a toothed segment 206 coupled to the base portion 204. Specifically, a first side 208 of the toothed segment 206 is coupled to the base portion 204 (e.g., via pins, brazing, or other mechanical coupling), and a second side 210 of the toothed segment 206 includes teeth 212. The toothed segment 206 is a sized to fit within a radially outer space 214 of the opening 128 of the open mouth sprocket 118. More specifically, the toothed segment 206 is a sized to occupy or fill the radially outer space 214 of the opening 128. For example, FIG. 7 is a cross-sectional axial view of the joint rotation system 50, taken along line 6-6 of FIG. 5, illustrating the latch 200 of FIG. 6 shown in a closed position. As shown, when the latch 200 is closed, the opening 128 of the open mouth sprocket 118 is enclosed. As will be appreciated, the latch 200 may be moved from the open position shown in FIG 6 to the closed position shown in FIG. 7 after the joint rotation system 50 is positioned about the tubulars 38 to be connected or disconnected. In certain embodiments, the latch 200 may be held in the closed position by a friction fit, interference fit, protuberance, or other feature disposed at a distal end 2 8 of the base portion 204 of the latch 200.

[0049] Additionally, when the latch 200 is in the closed position, the second side 210 of the toothed segment 206 aligns (e.g., circumferentially aligns) with the outer circumference 126 of the open mouth sprocket 118 to form a fully-toothed full circumference 220 of the open mouth sprocket 118. In other words, when the latch 200 is in the closed position, teeth (e.g., teeth 124 and 212) are arrayed about the full circumference (e.g., circumference 126) of the open mouth sprocket 118. As will be appreciated, this fully-toothed configuration enables improved transfer of rotational movement between the open mouth sprocket 118 and the first chain 140 when rotational movement is transferred from the first clamping mechanism 100 to the gear assembly 104. In particular, for any given angular position of the open mouth sprocket 1 18, the minimum portion 50 (e.g., minimum arc length) of the circumference 126 engaged with the first chain 140 will be fully arrayed with teeth (e.g., teeth 124 and/or 212), thereby improving transfer of rotational movement from the first clamping mechanism 100 to the gear assembly 104.

[0050] FIGS. 8 and 9 are cross-sectional axial views of the joint rotation system 50, taken along line 8-8 of FIG. 5, illustrating one of the open mouth sprockets 118 of the second clamping mechanism 102. As similarly discussed above with reference to FIGS. 6 and 7, the open mouth sprocket 118 of the second clamping mechanism 102 shown in FIG. 8 also has the latch 200, which is pivotably connected to the main portion 202 (e.g., a disk) of the open mouth sprocket 118 and is shown in an open position. The latch 200 includes the base portion 204 that is coupled to the main portion 202 of the open mouth sprocket 118, and the base portion 204 may be pivotably coupled to the main portion 202 via a hinge, pin, or other mechanism that enables pivoting of the latch 200. The latch 200 shown in FIGS. 8 and 9 includes similar elements and element numbers as the latch 200 shown in FIGS. 8 and 9. For example, the latch 200 includes the toothed segment 206 coupled to the base portion 204, where the toothed segment 206 has teeth 212. FIG. 9 shows the latch 200 in a closed position to enclose the opening 128 in the open mouth sprocket 118. As discussed above, when the latch 200 is in the closed position, the second side 210 of the toothed segment 206 aligns (e.g., circumferential ly aligns) with the outer circumference 126 of the open mouth sprocket 1 18 to form a fully-toothed full circumference 220 of the open mouth sprocket 118, which enables improved transfer of rotational movement between the open mouth sprocket 1 18 and the second chain 146 when rotational movement is transferred from the gear assembly 104 to the second clamping mechanism 102.

[0051] FIGS, 10 and 1 1 are top views of an embodiment of the joint rotation system 50. The illustrated embodiment includes the first and second clamping mechanisms 100 and 102 with open mouth sprockets 1 1 8 having latches 200 for selectively enclosing the respective openings 128 of the sprockets 1 18. in FIG. 10, the latches 200 of the open mouth sprockets 118 for the first and second clamping mechanisms 100 and 102 are shown in the open position. For example, a first latch 250 of one of the open mouth sprockets 8 of the first clamping mechanism 100 hmged and open on a first side 252 of the opening 128, and a second latch 254 of one of the open mouth sprockets 118 of the second clamping mechanism 102 hmged and open on a second side 256 of the opening 128 opposite the first side 252. In certain embodiments, the latches 200 of all open mouth sprockets 118 of the first clamping mechanism 100 may be hinged on the first side 252, while the latches 200 of all open mouth sprockets 118 of the second clamping mechanism 102 may be hinged on the second side 256. In other embodiments, the latches 200 of the first and second clamping mechanisms 100 and 102 may hinge to their respective open mouth sprocket 118 on alternating sides (e.g., alternating first side 252 and second side 256) from a top of the joint rotation system 50 to a bottom of the joint rotation system 50. In FIG. 11, all latches 200 are shown in the closed position to enclose the openings 128 of the open mouth sprockets 118.

[0052] The embodiments shown in FIGS. 10 and 11 also include other features of the joint rotation system 50. For example, the housing 106 includes slots 260 extending through the housing 106 from a top to a bottom of the housing 106 on opposite lateral sides 262 of the joint rotation system 50. As mentioned above, the external lifting frame 66 may further enable ergonomic manipulation of the joint rotation system 50 toward and/or away from the tubulars 38. In certain embodiments, one or more components of the external lifting frame 66 may extend through the slots 260 to support the joint rotation system 60 with the external lifting frame 66. The joint rotation system 50 may be configured to slide along the external lifting frame 66 extending through the slots 260 to enable axiaily positioning the joint rotation system 50 relative to the tubulars 38 to be coupled or decoupled using the joint rotation system.

[0053] Another feature shown in FIGS. 10 and 11 is motor and/or spring assembly 270 disposed on a top surface 272 of the housing 106. The motor and/or spring assembly 270 may be configured to rotate the open mouth sprockets 118 when the first and second clamping mechanisms 100 and 102 are disengaged from the tubulars 38. More specifically, the motor and/or spring assembly 270 is configured to rotate each of the open mouth sprockets 1 18 to an open or "home" position. In the open or "home" position, the opening 128 of each of the open mouth sprockets 18 of the first clamping mechanism 100 and second clamping mechanism 102 is axiaily aligned (e.g., relative to a central axis of the joint rotation system 50) with the other openings 128. Thus, in the open or "home" position, the joint rotation system 50 may be readily removed from the tubulars 38 and/or drill string 28.

[0054] As discussed above, embodiments of the present disclosure are directed toward the joint rotation system 50 to enable assembly and disassembly of lengths of tubular 38 to and from one another on a drilling rig. For example, the joint rotation system 50 may be used to thread and unthread lengths of drill pipe to and from one another to assemble or disassemble the drill string 28. As described above, the joint rotation system 50 is geared to grip and rotate two lengths of tubular 38 at different speeds while the top drive 40 or other rotational system rotates one of the lengths of tubular 38. Specifically, the joint rotation system 50 transfers rotational movement of one of the lengths of tubular 38 (e.g., driven by the top drive 40) to another length of tubular 38 at a gear or speed ratio greater than one to enable differential speed rotation of the other length of tubular 38 relative to the first length of tubular 38. As the joint rotation system 50 rotates the two lengths of tubular 38 at different speeds, the relative rotations (e.g., differential speeds) of the two lengths of tubular 38 enable engagement (e.g., threading) or disengagement (e.g., unthreading) of the lengths of tubular 38 to or from one another. The joint rotation system 50 includes two or more clamping mechanisms 100 and 102 configured to clamp the two lengths of tubular 38 to be threaded or unthreaded. For example, the joint rotation system 50 may include the first clamping mechanism 100 to grip a top tubular 38 and a second clamping mechanism 102 to grip a bottom tubular 38. Additionally, the clamping mechanisms 100 and 102 may have openings 128 (e.g., enclosable openings) that enable efficient coupling of the joint rotation system 50 to the two lengths of tubular 38 to be connected or disconnected from one another. In other words, the configuration of the clamping mechanisms 100 and 102 discussed above enables the joint rotation system 50 to be quickly and readily engaged and disengaged with lengths of tubular 38 to be connected or disconnected from one another.

[0055] While only certain features of the present disclosure have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the present disclosure.