Tool coupler with threaded connection for top drive

BACKGROUND OF THE INVENTION

0001Embodiments of the present invention generally relate to equipment and methods for coupling a top drive to one or more tools. The coupling may transfer both axial load and torque bi-directionally from the top drive to the one or more tools.

0002A wellbore is formed to access hydrocarbon-bearing formations (e.g., crude oil and/or natural gas) or for geothermal power generation by the use of drilling. Drilling is accomplished by utilizing a drill bit that is mounted on the end of a tool string. To drill within the wellbore to a predetermined depth, the tool string is often rotated by a top drive on a drilling rig. After drilling to a predetermined depth, the tool string and drill bit are removed, and a string of casing is lowered into the wellbore. Well construction and completion operations may then be conducted.

0003During drilling and well construction/completion, various tools are used which have to be attached to the top drive. The process of changing tools is very time consuming and dangerous, requiring personnel to work at heights. The attachments between the tools and the top drive typically include mechanical, electrical, optical, hydraulic, and/or pneumatic connections, conveying torque, load, data, signals, and/or power.

0004Typically, sections of a tool string are connected together with threaded connections. Such threaded connections are capable of transferring load. Righthand (RH) threaded connections are also capable of transferring RH torque. However, application of left-hand (LH) torque to a tool string with RH threaded connections (and vice versa) risks breaking the string. Methods have been employed to obtain bi-directional torque holding capabilities for connections. Some examples of these bi-directional setting devices include thread locking mechanisms for saver subs, hydraulic locking rings, set screws, jam nuts, lock washers, keys, cross/thru-bolting, lock wires, clutches and thread locking compounds. However, these solutions have shortcomings. For example, many of the methods used to obtain bi-directional torque capabilities are limited by friction between component surfaces or compounds that typically result in a relative low torque resistant connection. Locking rings may provide only limited torque resistance, and it may be difficult to fully monitor any problem due to limited accessibility and location. For applications that require high bi-directional torque capabilities, only positive locking methods such as keys, clutches or cross/through-bolting are typically effective. Further, some high bi-directional torque connections require both turning and milling operations to manufacture, which increase the cost of the connection over just a turning operation required to manufacture a simple male-to-female threaded connection. Some high bi-directional torque connections also require significant additional components as compared to a simple male-to-female threaded connection, which adds to the cost. <patcit id="pcit0001" dnum="US2005269104A"><text>US2005269104</text></patcit> describes a top drive system comprising a planetary gear system.

0005Safer, faster, more reliable, and more efficient connections that are capable of conveying load, data, signals, power and/or bi-directional torque between the tool string and the top drive are needed.

SUMMARY OF THE INVENTION

0006The present invention generally relates to equipment and methods for coupling a top drive to one or more tools. The coupling may transfer both axial load and torque bi-directionally from the top drive to the one or more tools. The present invention relates to a top drive system according to claim 1 and to a method of coupling a drive unit to a tool adapter according to claim 8. Further aspects and preferred embodiments are set out in claim 2 et seq.

BRIEF DESCRIPTION OF THE DRAWINGS

0007So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. <ul id="ul0001" list-style="none"><li><figref idref="f0001">Figure 1</figref> illustrates a drilling system.</li><li><figref idref="f0002">Figure 2</figref> illustrates a top drive system of the drilling system of <figref idref="f0001">Figure 1</figref>.</li><li><figref idref="f0003">Figures 3A-3B</figref> illustrates a drive stem of the top drive system of <figref idref="f0002">Figure 2</figref>.</li><li><figref idref="f0004">Figures 4A-4B</figref> illustrates a torque sleeve of the top drive system of <figref idref="f0002">Figure 2</figref>.</li><li><figref idref="f0004">Figures 5A-5B</figref> illustrates a tool stem of the top drive system of <figref idref="f0002">Figure 2</figref>.</li><li><figref idref="f0005 f0006 f0007">Figures 6A-6C</figref> illustrate coupling between a drive unit and a tool adapter of the top drive system of <figref idref="f0002">Figure 2</figref>.</li><li><figref idref="f0008">Figure 7</figref> illustrates a top drive system of the drilling system of <figref idref="f0001">Figure 1</figref>.</li><li><figref idref="f0009 f0010">Figures 8A-8B</figref> illustrates a spindle unit of the top drive system of <figref idref="f0008">Figure 7</figref>.</li><li><figref idref="f0011">Figures 9A-9C</figref> illustrate coupling between a drive unit and a tool adapter of the top drive system of <figref idref="f0008">Figure 7</figref>.</li><li><figref idref="f0012">Figure 10</figref> illustrates a top drive system of the drilling system of <figref idref="f0001">Figure 1</figref>.</li><li><figref idref="f0013">Figure 11</figref> illustrates a transmission unit of the top drive system of <figref idref="f0012">Figure 10</figref>.</li><li><figref idref="f0014">Figures 12A-12B</figref> illustrates a selection ring of the top drive system of <figref idref="f0012">Figure 10</figref>.</li><li><figref idref="f0015 f0016 f0017 f0018 f0019">Figures 13A-13E</figref> illustrate coupling between a drive unit and a tool adapter of the top drive system of <figref idref="f0012">Figure 10</figref>.</li></ul>

DETAILED DESCRIPTION

0008The present invention provides equipment and methods for coupling a top drive to one or more tools. The coupling may transfer torque bi-directionally from the top drive to the one or more tools. The coupling may provide mechanical, electrical, optical, hydraulic, and/or pneumatic connections. The coupling may conveying torque, load, data, signals, and/or power. For example, axial loads of tool strings may be expected to be several hundred tons, up to, including, and sometimes surpassing 750 tons. Required torque transmission may be tens of thousands of Kg. force-meter, up to, including, and sometimes surpassing 13825.5 kg. force-meter (tens of thousands of foot-pounds, up to, including, and sometimes surpassing 100 thousand foot-pounds). Embodiments disclosed herein may provide axial connection integrity, capable of supporting high axial loads, good sealability, resistance to bending, high flow rates, and high flow pressures.

0009Some of the many benefits provided by embodiments of this disclosure include a reliable method to transfer full bi-directional torque, thereby reducing the risk of accidental breakout of threaded connections along the tool string. Embodiments of this disclosure also provide a fast, hands-free method to connect and transfer power from the drive unit to the tool adapter. Embodiments provide automatic connection for power and data communications.

0010In some embodiments, the torque transfer path from the top drive system to the tool string bypasses the threaded connection between the drive unit and the tool adapter. This may allow full bi-directional torque to be applied in the tool string. This compares to systems wherein the torque transfer path proceeds through the threaded connections between the drive unit and the tool adapter which present a risk of backing out the main threaded connection while rotating in the breakout direction.

0011In an illustrative example not forming any part of the protected scope, <figref idref="f0001">Figure 1</figref> illustrates a drilling system 1. The drilling system 1 may include a drilling rig derrick 3d on a drilling rig floor 3f. As illustrated, drilling rig floor 3f is at the surface of a subsurface formation 7, but the drilling system 1 may also be an offshore drilling unit, having a platform or subsea wellhead in place of or in addition to rig floor 3f. The derrick may support a hoist 5, thereby supporting a top drive 4. In an illustrative example not forming any part of the protected scope, the hoist 5 may be connected to the top drive 4 by threaded couplings. The top drive 4 may be connected to a tool string 2. At various times, top drive 4 may support the axial load of tool string 2. In an illustrative example not forming any part of the protected scope, the top drive 4 may be connected to the tool string 2 by threaded couplings. The rig floor 3f may have an opening through which the tool string 2 extends downwardly into a wellbore 9. At various times, rig floor 3f may support the axial load of tool string 2. During operation, top drive 4 may provide torque to tool string 2, for example to operate a drilling bit near the bottom of the wellbore 9. The tool string 2 may include joints of drill pipe connected together, such as by threaded couplings. At various times, top drive 4 may provide right hand (RH) torque or left hand (LH) torque to tool string 2, for example to make up or break out joints of drill pipe. Power and/or signals may be communicated between top drive 4 and tool string 2. For example, pneumatic, hydraulic, electrical, optical, or other power and/or signals may be communicated between top drive 4 and tool string 2. The top drive 4 may include a control unit, a drive unit, and a tool adapter. In an illustrative example not forming any part of the protected scope, the tool adapter may utilize threaded connections. In an illustrative example not forming any part of the protected scope, the tool adapter may be a combined multi-coupler (CMC) or quick connector to support load and transfer torque with couplings to transfer power (hydraulic, electric, data, and/or pneumatic).

0012In an illustrative example not forming any part of the protected scope, <figref idref="f0002">Figure 2</figref> illustrates a top drive system 100 (e.g., top drive 4 in <figref idref="f0001">Figure 1</figref>). Generally, top drive system 100 includes a drive unit 110 and a tool adapter 150. The drive unit 110 generally includes a housing 120, becket 125, drive gears 130, motors 140 (e.g., electric or hydraulic motors), first portions of one or more couplings 170, a drive stem 180, and a torque sleeve 190. Becket 125 may convey load from the top drive system 100 to the hoist 5. Becket 125 may be used with, or replaced by, other load-transfer components. Drive gears 130 may couple to motors 140 by way of shaft 135. Drive gears 130 may convey torque between the motors 140 and the drive stem 180. As illustrated, top drive system 100 includes two drive gears 130 (only one shown in <figref idref="f0002">Figure 2</figref>) and two motors 140. Any number of drive gears 130 and/or motors 140 may be considered to accommodate manufacturing and operational conditions. The motors 140 may be fixed relative to the housing 120. The drive stem 180 may extend through an interior of torque sleeve 190. The tool adapter 150 generally includes a tool stem 160 and second portions of the couplings 170. Couplings 170 may include complementary components disposed in or on drive unit 110 and tool adapter 150. The tool stem 160 generally remains below the drive unit 110. (It should be understood that "below", "above", "vertically", "up", "down", and similar terms as used herein refer to the general orientation of top drive 4 as illustrated in <figref idref="f0001">Figure 1</figref>. In some instances, the orientation may vary somewhat, in response to various operational conditions. In any instance wherein the central axis of the top drive system is not aligned precisely with the direction of gravitational force, "below", "above", "vertically", "up", "down", and similar terms should be understood to be along the central axis of the top drive system.) The tool stem 160 connects the top drive system 100 to the tool string 2. The tool stem 160 and drive stem 180 may share a central bore 165 (e.g. providing fluid communication through the top drive system 100 to the tool string 2). Couplings 170 may include, for example, threaded couplings, hydraulic couplings, pneumatic couplings, electronic couplings, fiber optic couplings, power couplings, data couplings, and/or signal couplings. When the drive unit 110 is coupled to the tool adapter 150, top drive system 100 may transfer bi-directional torque, load, power, data, and/or signals between the top drive and the tool.

0013As illustrated in <figref idref="f0003">Figure 3</figref>, drive stem 180 may have two gear profiles: drive gear profile 185 and torque gear profile 195. Drive gears 130 (<figref idref="f0002">Figure 2</figref>) may engage drive stem 180 at drive gear profile 185. Motors 140 may turn shaft 135, which turns drive gears 130, thereby turning drive gear profile 185 and drive stem 180. Drive gear profile 185 may have teeth designed to mesh with the gearing of drive gears 130. Alternatively, drive gears 130 and/or drive gear profile 185 may be configured to engage belt drive, chain drive, or other systems that are capable of conveying rotation. Also illustrated in <figref idref="f0003">Figure 3</figref>, the drive stem 180 may be encircled by swivel 174, centering ring 181, and/or seal sleeve 182. The centering ring 181 may provide rigidity to the connection, for example, resisting bending forces. The centering ring 181 may assist in alignment of seals, couplers, and/or data connectors. For example, the centering ring 181 may provide for proper alignment between the drive stem 180 and the seal package 163 (<figref idref="f0004">Figure 5B</figref>) of the tool stem 160. The fit between the centering ring 181 and the tool stem 160 may control or reduce play between the components, thereby improving the sealing performance. The coupling between drive stem 180 and seal sleeve 182 may include a threaded coupling 183 and/or one or more O-rings 184. The O-rings 184 may engage the inner diameter of the seal sleeve 182 to reduce or prevent high pressure fluid leakage out of the connection. The seal sleeve 182 may be incorporated as a replaceable component of the drive unit 110. Also illustrated in <figref idref="f0003">Figure 3</figref>, a portion of the exterior of drive stem 180 may include a threaded coupling 186. As illustrated, threaded coupling 186 is disposed between centering ring 181 and torque gear profile 195, but threaded coupling 186 may also be disposed at other locations along the length of drive stem 180. When the drive unit 110 is coupled to the tool adapter 150, threaded coupling 186 may provide a load coupling between drive stem 180 and tool stem 160. Threaded coupling 186 may be a heavy-load capacity thread (e.g., stub acme thread).

0014As illustrated in <figref idref="f0004">Figure 4A</figref>, at least a portion of the interior of torque sleeve 190 may include a sleeve gear profile 192. Sleeve gear profile 192 may engage torque gear profile 195 when torque sleeve 190 is in a lowered position (shown in <figref idref="f0007">Figure 6C</figref>). When torque sleeve 190 is in a lowered position, drive stem 180 may turn torque gear profile 195, which engages sleeve gear profile 192, thereby turning torque sleeve 190.

0015As illustrated in <figref idref="f0004">Figure 5A</figref>, tool stem 160 may have a stem gear profile 162 on at least a portion of an exterior surface near the top of the tool stem 160. Sleeve gear profile 192 may engage stem gear profile 162 when torque sleeve 190 is in a lowered position (shown in <figref idref="f0007">Figure 6C</figref>). When torque sleeve 190 is in a lowered position, drive stem 180 may turn torque gear profile 195, which engages sleeve gear profile 192, which engages stem gear profile 162, thereby turning tool stem 160. As illustrated in <figref idref="f0004">Figure 5B</figref>, tool stem 160 may have a seal package 163 disposed in the central bore 165. When the drive unit 110 is coupled to the tool adapter 150, the seal package 163 may provide a seal of the central bore 165 between the drive stem 180 and the tool stem 160. The seal package 163 may be located adjacent to a shoulder 164 or in a recess (not shown) of the interior of tool stem 160. The seal package may include high pressure-high temperature (HPHT) dynamic seals. For example, the seal package may seal the central bore 165 up to pressures of about 15k psi. Also illustrated in <figref idref="f0004">Figure 5B</figref>, tool stem 160 may have a threaded coupling on at least a portion of an interior surface near the top of the tool stem 160.

0016Drive unit 110 may be coupled to tool adapter 150 in order to transfer bi-directional torque, load, power, data, and/or signals between the top drive and the tool. Coupling of drive unit 110 to tool adapter 150 may proceed as a multi-step process. In an illustrative example not forming any part of the protected scope, as illustrated in <figref idref="f0005 f0006">Figures 6A-6B</figref>, the coupling begins with axial load coupling between drive stem 180 and tool stem 160. Drive stem 180 may be aligned with tool stem 160 so that a lower portion of drive stem 180 may be stabbed into tool stem 160. For example, drive stem 180 may be lowered relative to tool stem 160, and/or tool stem 160 may be raised relative to drive stem 180. Drive stem 180 may rotate relative to tool stem 160 so that threaded coupling 186 on drive stem 180 engage and mate with threaded coupling 166 on tool stem 160 (<figref idref="f0006">Figure 6B</figref>). Threaded coupling 166 may be a heavy-load capacity thread (<i>e.g.,</i> stub acme thread). An exterior surface of seal sleeve 182 may contact and/or engage with seal package 163.

0017Motors 140 may provide torque to make up or break out the axial load connection between tool stem 160 and drive stem 180. For example, motors 140 may turn shaft 135, which turns drive gears 130, thereby turning drive gear profile 185 and drive stem 180. Threaded coupling 186 on drive stem 180 may engage and mate with threaded coupling 166 on tool stem 160. Torque of drive stem 180 may cause threading (or unthreading, depending on direction) between tool stem 160 and drive stem 180. The drive stem 180 may have RH male threading, while the tool stem 160 may have RH female threading. When tool stem 160 is coupled to drive stem 180, as shown in <figref idref="f0006">Figure 6B</figref>, axial load may be transferred between the top drive and the tool. Likewise, when tool stem 160 is coupled to drive stem 180, central bore 165 may provide fluid communication between the top drive and the tool. It should be appreciated that, when tool stem 160 is coupled to drive stem 180, torque in the direction of the threaded couplings 186/166 may also be transferred between the top drive and the tool. For example, torque may be transferred from the motors 140 through shaft 135 to the drive gears 130, through drive gear profiles 185 to the drive stem 180, through the threaded couplings 186/166, to the tool stem 160, and to the tool string 2.

0018Coupling of drive unit 110 to tool adapter 150 may proceed with bi-directional torque coupling between torque sleeve 190 and tool stem 160, as illustrated in <figref idref="f0006 f0007">Figures 6B-6C</figref>. The drive stem 180 may extend through an interior of torque sleeve 190. Torque sleeve 190 may move vertically relative to drive stem 180. For example, actuators 191 (<i>e.g</i>., hydraulic or pneumatic cylinders, or electric actuators) on drive stem 180 may move torque sleeve 190 between a raised position and a lowered position. While tool stem 160 is load coupling with drive stem 180, as shown in <figref idref="f0005 f0006">Figures 6A-6B</figref>, torque sleeve 190 may be in the raised position (relative to drive stem 180). Torque sleeve 190 may then move to the lowered position (relative to drive stem 180; <figref idref="f0007">Figure 6C</figref>) to engage tool stem 160, thereby transferring torque. For example, sleeve gear profile 192 on an interior surface of torque sleeve 190 may engage torque gear profile 195 of drive stem 180 when torque sleeve 190 is in the lowered position (shown in <figref idref="f0007">Figure 6C</figref>). Drive stem 180 may turn torque gear profile 195 to engage sleeve gear profile 192, thereby turning torque sleeve 190, and sleeve gear profile 192 may also engage stem gear profile 162, thereby turning tool stem 160.

0019Once torque sleeve 190 has moved to a lowered position and coupled to tool stem 160, as shown in <figref idref="f0007">Figure 6C</figref>, bi-directional torque may be transferred between the top drive and the tool. For example, torque gear profile 195 of drive stem 180 may engage sleeve gear profile 192 of torque sleeve 190, which, when in the lowered position, also engages stem gear profile 162, thereby providing torque to tool stem 160 during drilling operations. Bi-directional torque may be thereby transferred from the motors 140 of the drive unit 110 to the tool stem 160, and thus to the tool string 2.

0020In an illustrative example not forming any part of the protected scope, coupling drive unit 110 to tool adapter 150 may be facilitated with various sensors, actuators, couplers, and/or adapters. For example, couplings 170 may include one or more hydraulic, pneumatic, electrical, or optical couplings, providing fluid, electrical, optical, signal, data, and/or power communication between the drive unit 110 and the tool adapter 150. Couplings 170 may include tool stem connectors 171 (<figref idref="f0004">Figure 5B</figref>) and mating torque sleeve connectors 172 (<figref idref="f0004">Figure 4B</figref>). connectors 171/172 may communicate signals (e.g., hydraulic, pressure, fluid, data, optical, electrical, etc.) from the drive unit 110 to the tool adapter 150. Alternatively, connectors 172 may be incorporated on drive stem 180.

0021As another example, couplings 170 may include a swivel 174 (<i>e.g.,</i> a hydraulic swivel or a pneumatic swivel) along drive stem 180. Swivel 174 may be disposed co-axially with drive stem 180. Swivel 174 may encircle drive stem 180. In an illustrative example not forming any part of the protected scope, swivel 174 may be fixed relative to housing 120 while allowing rotation between swivel 174 and drive stem 180. In an illustrative example not forming any part of the protected scope, swivel 174 may be fixed relative to drive stem 180 while allowing rotation between swivel 174 and housing 120. In an illustrative example not forming any part of the protected scope, swivel 174 may be free to rotate both relative to drive stem 180 and housing 120.

0022As another example, coupling drive unit 110 to tool adapter 150 may be facilitated with various sensors. The torque sleeve 190 may have sensors 173 (<figref idref="f0004">Figure 4B</figref>) located near its lower edge to ease the alignment process between the couplings 170 located on the drive unit 110 and mating couplings 170 located on the tool adapter 150.

0023In an illustrative example not forming any part of the protected scope, <figref idref="f0008">Figure 7</figref> illustrates an alternative top drive system 200. Except as noted, top drive system 200 is configured and functions similarly to top drive system 100. For example, top drive system 200 includes a drive unit 210 and a tool adapter 250. The drive unit 210 generally includes a housing 220, becket 225, drive gears 230, motors 240, first portions of one or more couplings 270, and a drive stem 280. Rather than torque sleeve 190, drive unit 210 includes a spindle unit 290. Rather than actuators 191, drive unit 210 includes an annular motor 291 (<i>e.g.</i>, hydraulic or electric motor) operationally coupled to components of the spindle unit 290. The drive stem 280 may extend through an interior of spindle unit 290. In an illustrative example not forming any part of the protected scope, at least a portion of the annular motor 291 may be fixed relative to the drive stem 280. The tool adapter 250 generally includes a tool stem 260 and second portions of the couplings 270. The tool stem 260 connects the top drive system 200 to the tool string 2. The tool stem 260 and drive stem 280 may share a central bore 265. When the drive unit 210 is coupled to the tool adapter 250, top drive system 200 may transfer bi-directional torque, load, power, data, and/or signals between the top drive and the tool.

0024As illustrated in <figref idref="f0009">Figure 8A</figref>, spindle unit 290 generally includes annular motor 291, a spindle 293, and a counter nut 294. The drive stem 280 may extend through interiors of annular motor 291, spindle 293, and/or counter nut 294. Annular motor 291 is configured to rotate spindle 293 relative to drive stem 280. In an illustrative example not forming any part of the protected scope, a portion of annular motor 291 is fixed to drive stem 280. In an illustrative example not forming any part of the protected scope, a portion of annular motor 291 is rotationally coupled to spindle 293. An example of a suitable annular motor is a 1 MB frameless, maintenance-free asynchronous motor with high power density, available from Bosch Rexroth AG of Lohr, Germany. In the illustrated embodiment, annular motor 291 includes a fixed portion 291-f that is fixed to drive stem 280, and a rotatable portion 291-r that is rotatable relative to drive stem 280. As illustrated, rotatable portion 291-r is rotationally coupled to spindle 293. For example, rotatable portion 291-r is coupled to a flange 292, which is coupled to spindle 293. In an illustrative example not forming any part of the protected scope, flange 292 and spindle 293 are permanently fixed together and/or formed as a unified component. Annular motor 291 may thereby drive rotation in spindle 293 by rotating rotatable portion 291-r relative to fixed portion 291-f. In an illustrative example not forming any part of the protected scope, annular motor 291 includes gearing, wheels, tracks, etc., capable of conveying rotational motion (relative to drive stem 280) to spindle 293. Counter nut 294 may move vertically relative to drive stem 280 and/or spindle 293 Annular motor 291 may provide torque, thereby rotating spindle 293 relative to drive stem 280. Spindle 293 may have internal threading, and counter nut 294 may have external threading, for example threading 294-t (<figref idref="f0010">Figure 8B</figref>). Spindle 293 may thereby mate with and/or engage counter nut 294. Drive stem 280 may have an external guide profile proximate the spindle unit 290, and counter nut 294 may have an internal guide profile, for example guide profile 294-g (<figref idref="f0010">Figure 8B</figref>). Counter nut 294 may thereby mate with and/or engage drive stem 280. Engagement of the guide profiles may prevent rotation between counter nut 294 and drive stem 280. Also illustrated in <figref idref="f0009">Figure 8A</figref>, a portion of the exterior of drive stem 280 may include a threaded coupling 286.

0025As before, coupling of drive unit 210 to tool adapter 250 may proceed as a multi-step process. In an illustrative example not forming any part of the protected scope, illustrated in <figref idref="f0011">Figures 9A-9B</figref>, the coupling begins with axial load coupling between drive stem 280 and tool stem 260. Drive stem 280 may be aligned with tool stem 260 so that a lower portion of drive stem 280 may be stabbed into tool stem 260. Drive stem 280 may rotate relative to tool stem 260 so that threaded coupling 286 on drive stem 280 engages and mates with threaded coupling 266 on tool stem 260 (<figref idref="f0011">Figure 9B</figref>). Spindle unit 290 may remain fixed relative to drive stem 280 during axial load coupling. For example, annular motor 291 may reduce or prevent rotation of spindle unit 290 relative to drive stem 280 during axial load coupling. Counter nut 294 may be in a raised position relative to drive stem 280 during axial load coupling.

0026Motors 240 may provide torque to make up or break out the axial load connection between tool stem 260 and drive stem 280. Torque of drive stem 280 may cause threading (or unthreading, depending on direction) between tool stem 260 and drive stem 280. Threaded coupling 286 of drive stem 280 may be RH male threading, while threaded coupling 266 of tool stem 260 may be RH female threading. When tool stem 260 is coupled to drive stem 280, as shown in <figref idref="f0011">Figure 9B</figref>, axial load may be transferred between the top drive and the tool. Likewise, when tool stem 260 is coupled to drive stem 280, central bore 265 may provide fluid communication between the top drive and the tool. It should be appreciated that, when tool stem 260 is coupled to drive stem 280, torque in the direction of the threaded couplings 286/266 may also be transferred between the top drive and the tool. For example, torque may be transferred from the motors 240 through shaft 235 to the drive gears 230, through drive gear profiles 285 to the drive stem 280, through the threaded couplings 286/266, to the tool stem 260, and to the tool string 2.

0027Coupling of drive unit 210 to tool adapter 250 may proceed with bi-directional torque coupling between drive stem 280 and tool stem 260, as illustrated in <figref idref="f0011">Figures 9B-9C</figref>. Annular motor 291 may rotate spindle 293 relative to drive stem 280. Annular motor 291 may thereby rotate spindle 293 relative to counter nut 294. Rotation of spindle 293 relative to counter nut 294 may cause vertical motion of counter nut 294 due to the threaded coupling between spindle 293 and counter nut 294 (<i>e.g</i>., threading 294-t on counter nut 294) and the guided coupling between drive stem 280 and counter nut 294 (<i>e.g</i>., guide profile 294-g on counter nut 294). During torque coupling, rotation of spindle 293 may continue until counter nut 294 contacts tool stem 260 (<figref idref="f0011">Figure 9C</figref>). For example, counter nut 294 may contact shoulder 261 of tool stem 260. Shoulder 261 may be proximate a top of tool stem 260. During operation, engagement between counter nut 294 and shoulder 261 may be maintained, for example by a locking mechanism (<i>e.g</i>., hydraulic), and/or by continued torque from annular motor 291. In an illustrative example not forming any part of the protected scope, rotation of drive stem 280 in a direction ("loosening direction") that would break up or loosen the connection between threaded coupling 266 and threaded coupling 286 may thereby also force counter nut 294 downwards relative to drive stem 280. Once counter nut 294 contacts tool stem 260 (<figref idref="f0011">Figure 9C</figref>), further rotation of drive stem 280 in the loosing direction may serve to transfer torque to tool stem 260. Likewise, rotation of drive stem 280 in the opposite direction ("tightening direction") may serve to transfer torque to tool stem 260 through the connection of threaded coupling 266 with threaded coupling 286.

0028De-coupling drive unit 210 from tool adapter 250 includes reverse rotation of spindle 293. Annular motor 291 may reverse the rotation of spindle 293, and thereby raising counter nut 294 relative to drive stem 280. Movement of counter nut 294 away from contact with tool stem 260 (<figref idref="f0011">Figure 9B</figref>) allows rotation of drive stem 280 in the loosening direction to break up or loosen the connection between threaded coupling 266 and threaded coupling 286.

0029<figref idref="f0012">Figure 10</figref> illustrates an alternative top drive system 300 according to embodiments of the invention described herein. Except as noted, top drive system 300 is configured and functions similarly to top drive system 100 and top drive system 200. For example, top drive system 300 includes a drive unit 310 and a tool adapter 350. The drive unit 310 generally includes a housing 320, becket 325, drive gears 330, motors 340, first portions of one or more couplings 370, and a drive stem 380. Rather than torque sleeve 190 or spindle unit 290, drive unit 310 includes a (torque) transmission unit 390. Rather than actuators 191 or annular motor 291, drive unit 310 includes a swivel 321 and a selection ring 395. The drive stem 380 may extend through an interior of torque transmission unit 390 and an interior of selection ring 395. At least a portion of swivel 321 may be fixed relative to the housing 320, and swivel 321 may encircle drive stem 380. For example, swivel 321 may include a stationary portion 321-s that is fixed relative to housing 320 and a rotatable portion 321-r that may rotate relative to housing 320. In some embodiments, the rotatable portion 321-r may be rotationally fixed to selection ring 395. The stationary portion 321-s may encircle the rotatable portion 321-r. Drive stem 380 may have friction surfaces 387 that parallel and may engage with friction surfaces 397 of transmission unit 390. The tool adapter 350 generally includes a tool stem 360 and second portions of the couplings 370. The tool stem 360 connects the top drive system 300 to the tool string 2. The tool stem 360 and drive stem 380 may share a central bore 365. When the drive unit 310 is coupled to the tool adapter 350, top drive system 300 may transfer bi-directional torque, load, power, data, and/or signals between the top drive and the tool.

0030As illustrated in <figref idref="f0013">Figure 11</figref>, transmission unit 390 generally includes couplings 370, one or more shoulders 394 proximate a bottom of the transmission unit 390, one or more coupling holes 391 proximate a top of the transmission unit 390, and one or more friction surfaces 397. The drive stem 380 may extend through the interior of transmission unit 390. Friction surfaces 387 of drive stem 380 may parallel and may engage with friction surfaces 397 of transmission unit 390. As illustrated, drive stem 380 includes eight disks projecting radially outward, each disk having two friction surfaces 387 (<i>i.e.,</i> a top surface and a bottom surface). As illustrated, transmission unit 390 has nine annular disks encircling drive stem 380 and interleaved with the eight disks of the drive stem 380, each of the annular disks having one or two friction surfaces 397 (<i>i.e</i>., a top surface and a bottom surface). As would be understood by one of ordinary skill in the art with the benefit of this disclosure, other configurations of drive stem friction surfaces 387 and transmission unit friction surfaces 397 may be considered to accommodate manufacturing and operational conditions. Friction surfaces 387/397 may be selectively engaged. For example, a transmission selector 393 (<figref idref="f0014">Figure 12</figref>) from selection ring 395 may be actuated (<i>e.g</i>., hydraulically) to apply a compressive (normal) force to the interleaved friction surfaces 387/397. Engagement of friction surfaces 387 with friction surfaces 397 may rotationally couple drive stem 380 with transmission unit 390. Also illustrated in <figref idref="f0013">Figure 11</figref>, a portion of the exterior of drive stem 380 may include a threaded coupling 386. Shoulders 394 may convey torque between transmission unit 390 and tool stem 360. As illustrated, shoulders 394 may be disposed on an interior surface of transmission unit 390. Complementary shoulders 364 may be disposed on an exterior surface of tool stem 360 (<figref idref="f0015">Figure 13A</figref>). The shoulders 394/364 may have guiding chamfers. It should be appreciated that other torque coupling types and/or configurations may be considered to accommodate manufacturing and operational conditions.

0031As illustrated in <figref idref="f0014">Figures 12A-12B</figref>, selection ring 395 includes one or more coupling pins 396 engagable with coupling holes 391 of transmission unit 390, one or more swivel selector 392 and one or more transmission selector 393. The coupling pins 396 may be actuated (<i>e.g</i>., hydraulically) to engage with coupling holes 391, thereby rotationally fixing selection ring 395 with transmission unit 390. Each selector 392/393 may be movable to an "on" position or an "off" position. The drive stem 380 may extend through an interior of selection ring 395. When swivel selector 392 is "on", selection ring 395 may move synchronously with stationary portion 321-s of swivel 321. For example, swivel selector 392 may include a pin that moves between an upper position (<figref idref="f0014">Figure 12A</figref>) and a lower position (<figref idref="f0014">Figure 12B</figref>). When the pin of swivel selector 392 is in the upper position, the swivel selector 392 is "on", and selection ring 395 may move synchronously with stationary portion 321-s of swivel 321. Likewise, transmission selector 393 may include a pin that moves between an upper position (<figref idref="f0014">Figure 12A</figref>) and a lower position (<figref idref="f0014">Figure 12B</figref>). Transmission selector 393 may engage transmission unit friction surfaces 397 with drive stem friction surfaces 387. For example, transmission selector 393 may compress transmission unit friction surfaces 397 against drive stem friction surfaces 387. When the pin of transmission selector 393 is in the lower position, the transmission selector 393 is "on", and friction surfaces 387 may engage with friction surfaces 397 to rotationally couple drive stem 380 with transmission unit 390. Likewise, when transmission unit friction surfaces 397 are engaged with drive stem friction surfaces 387, rotation of drive stem 380 may transmit torque to transmission unit 390. It should be appreciate that coupling pins 396 will be engaged with coupling holes 391 whenever transmission selector 393 is in the "on" position. Consequently, when the transmission selector 393 is "on", selection ring 395 may move synchronously with transmission unit 390. In some embodiments, swivel selector 392 and transmission selector 393 may be a single unit. In some embodiments, swivel selector 392 and/or transmission selector 393 may include or be actuated by a hydraulic cylinder. As would be understood by one of ordinary skill in the art with the benefit of this disclosure, other configurations of swivel selectors 392 and transmission selectors 393 may be considered to accommodate manufacturing and operational conditions.

0032In some embodiments, rather than coupling holes 391 in transmission unit 390 and coupling pins 396 of selection ring 395, transmission unit 390 may simply be fixed to selection ring 395. It should be appreciated that coupling holes 391 and coupling pins 396 may be beneficial for maintenance purposes.

0033As before, coupling of drive unit 310 to tool adapter 350 may proceed as a multi-step process. In one embodiment, illustrated in <figref idref="f0015 f0016 f0017">Figures 13A-13C</figref>, the coupling begins with axial load coupling between drive stem 380 and tool stem 360. Drive stem 380 may be aligned with tool stem 360 so that a lower portion of drive stem 380 may be stabbed into tool stem 360. Transmission unit 390 may also be aligned with tool stem 360 so that shoulders 394 align with corresponding shoulders 364 on tool stem 360. For example, shoulders 394 may include concave features on an interior surface of transmission unit 390, while corresponding shoulders 364 include convex features on an exterior surface of tool stem 360. In some embodiments, as illustrated in <figref idref="f0014">Figure 12B</figref>, transmission selector 393 may be initially moved to "on," swivel selector 392 may be initially moved to "off," and coupling pins 396 may engage coupling holes 391, so that rotation of drive stem 380 may be used to align transmission unit 390 with tool stem 360. Once transmission unit 390 is aligned with tool stem 360, transmission selector 393 may then be moved to "off" to allow free rotation of drive stem 380 relative to transmission unit 390. Drive stem 380 may rotate relative to tool stem 360 so that threaded coupling 386 on drive stem 380 engage and mate with threaded coupling 366 on tool stem 360 (<figref idref="f0016 f0017">Figures 13B-13C</figref>). In some embodiments, transmission unit 390 may remain fixed relative to housing 320 during axial load coupling. For example, swivel selector 392 may be set to "on" and coupling pins 396 may engage coupling holes 391 during axial load coupling. Selection ring 395 may thereby synchronize with stationary portion 321-s of swivel 321, which may be fixed relative to the housing 320. Likewise, transmission selector 393 may be "off" during axial load coupling, so transmission unit friction surfaces 397 may not be engaged with drive stem friction surfaces 387. Consequently, transmission unit 390 may not rotate with drive stem 380 during axial load coupling.

0034Motors 340 may provide torque to make up or break out the axial load connection between tool stem 360 and drive stem 380. Torque of drive stem 380 may cause threading (or unthreading, depending on direction) between tool stem 360 and drive stem 380. Threaded coupling 386 of drive stem 380 may be RH male threading, while threaded coupling 366 of tool stem 260 may be RH female threading. When tool stem 360 is coupled to drive stem 380, as shown in <figref idref="f0017">Figure 13C</figref>, axial load may be transferred between the top drive and the tool. Likewise, when tool stem 360 is coupled to drive stem 380, central bore 365 may provide fluid communication between the top drive and the tool. When tool stem 360 is coupled to drive stem 380, as shown in <figref idref="f0017">Figure 13C</figref>, couplings 370 may communicate pneumatic, hydraulic, electrical, optical, or other power and/or signals between drive unit 310 and tool adapter 350. In some embodiments, swivel 321 may provide torque to make up or break out the threaded coupling 366. For example, a rotational actuator may be coupled between housing 320 and stationary portion 321-s of swivel 321. Stationary portion 321-s may not be rotationally fixed to housing 320, but may have some rotational freedom of movement (e.g., less than about 60 degrees). In such embodiments, swivel 321 may be used as a wrenching tong for make up if the motors 340 cannot apply sufficient torque.

0035Coupling of drive unit 310 to tool adapter 350 may proceed with bi-directional torque coupling between drive stem 380 and tool stem 360, as illustrated in <figref idref="f0017 f0018 f0019">Figures 13C-13E</figref>. Shoulders 394 on transmission unit 390 may align and mate with corresponding shoulders 364 on tool stem 360. It should be appreciated that, immediately following axial load coupling, residual torque may exist in tool string 2. Drive stem 380 may counter the residual torque while making-up threaded coupling 366 (<figref idref="f0016 f0017">Figures 13B-13C</figref>). In some embodiments, drive stem 380 may be rotationally coupled to transmission unit 390 following axial load coupling to further counter the residual torque. For example, transmission selector 393 may be moved to "on," while swivel selector 392 may remain "on," and coupling pins 396 may continue engage coupling holes 391 (<figref idref="f0018">Figure 13D</figref>). Selection ring 395 may then safely switch from having swivel selector 392 "on" (<figref idref="f0015 f0016 f0017 f0018">Figures 13A-13D</figref>) to having swivel selector 392 "off" (<figref idref="f0019">Figure 13E</figref>). For example, residual torque may be transferred from tool string 2 through tool stem 360 to shoulders 364, to shoulders 394, and to transmission unit 390. With transmission selector 393 "on," swivel selector 392 "off," and coupling pins 396 engaged with coupling holes 391, selection ring 395 and transmission unit 390 may both rotationally synchronize with drive stem 380. Drive stem 380 may thereby counter any residual torque from tool string 2. Likewise, once shoulders 394 mate with corresponding shoulders 364, and once transmission selector 393 is "on", as shown in <figref idref="f0019">Figure 13E</figref>, bi-directional torque may be transferred between the top drive and the tool. For example, torque may be transferred from the motors 340 through shaft 335 (not shown) to the drive gears 330, to the drive stem 380, through the friction surfaces 387/397 to the transmission unit 390, through the mated shoulders 394/364 to tool stem 360, and to the tool string 2. Bi-directional torque may be thereby transferred from the motors 340 of the drive unit 310 to the tool stem 360, and thus to the tool string 2.

0036In some embodiments, coupling drive unit 310 to tool adapter 350 may be facilitated with various sensors, cameras, actuators, couplers, and/or adapters. For example, signals and/or power may be transferred between the rotatable portion 321-r of swivel 321 and the selection ring 395 by connections 322 (<figref idref="f0014">Figure 12</figref>). In some embodiments, swivel selector 392 and transmission selector 393 are hydraulic cylinders, and connections 322 may provide hydraulic control signals to swivel selector 392 and transmission selector 393. As another example, signals and/or power may be transferred between transmission unit 390 and tool stem 360 by couplings 370.

0037As another example, coupling drive unit 310 to tool adapter 350 may be facilitated with sensors to detect misalignments between components. For example, in the illustrated embodiment, when swivel selector 392 is "on" (<figref idref="f0015">Figure 13A</figref>), swivel selector 392 extends from selection ring 395 into a recess of swivel 321. Rotational misalignment of selection ring 395 and swivel 321 would not allow swivel selector 392 to extend from selection ring 395 into the recess of swivel 321. A sensor (<i>e.g</i>., an optical sensor) may be disposed on an upper portion of selection ring 395 to detect orientation relative to swivel 321. Appropriate alignment of selection ring 395 with swivel 321 may be achieved prior to actuating swivel selector 392. As another example, transmission unit 390 may be first oriented relative to tool stem 360 so that shoulders 394 align with shoulders 364. A sensor (<i>e.g.,</i> an optical sensor) may be disposed at the base of transmission unit 390. The sensor may be configured to detect a marker (<i>e.g.</i>, a reflector) disposed at the top of tool stem 360. Transmission unit 390 may be rotated relative to tool stem 360 until the sensor detects alignment with the marker. In some embodiments, multiple markers may be utilized. For example, transmission unit 390 may be appropriately oriented in two or more orientations relative to tool stem 360. The sensor need only detect alignment with the first marker to identify appropriate orientation of transmission unit 390 relative to tool stem 360.

0038As another example, coupling drive unit 310 to tool adapter 350 may be facilitated with adapters to allow for slight misalignments between components. For example, connections 322 may include a retractable adapter that allows for slight misalignments. In some embodiments, adapters may allow for connection 322 to be made between the rotatable portion 321-r of swivel 321 and selection ring 395 even with slight rotational and/or positional misalignment. Once connection 322 has been made, the adapter may maintain connection 322 f while selection ring 395 moves synchronously with swivel 321, even if a slight misalignment develops.

0039As another example, coupling drive unit 310 to tool adapter 350 may be facilitated with remote control actuators. For example, swivel selector 392 and/or transmission selector 393 may be remotely controlled.

0040It should be appreciated that, for each top drive system 100, 200, 300, other sensors, actuators, and/or adapters types and/or configurations may be considered to accommodate manufacturing and operational conditions. The actuators may be, for example, worm drives, hydraulic cylinders, compensation cylinders, etc. The actuators may be hydraulically, pneumatically, electrically, and/or manually controlled. In some embodiments, multiple control mechanism may be utilized to provide redundancy. One or more sensors may be used to monitor relative positions of the components of the top drive system. The sensors may be position sensors, rotation sensors, pressure sensors, optical sensors, magnetic sensors, etc. In some embodiments, stop surfaces may be used in conjunction with or in lieu of sensors to identify when components are appropriately positioned and/or oriented. Likewise, optical guides may be utilized to identify or confirm when components are appropriately positioned and/or oriented. In some embodiments, guide elements (<i>e.g</i>., pins and holes, chamfers, etc.) may assist in aligning and/or orienting the components of the top drive system 100, 200, 300. Bearings and seals may be disposed between components to provide support, cushioning, rotational freedom, and/or fluid management.

0041In an illustrative example not forming any part of the protected scope, a drive unit of a top drive system includes a drive stem having a torque gear profile and a load coupling, wherein the load coupling is a threaded coupling; and a torque sleeve movable between a first position and a second position, and having a sleeve gear profile that engages the torque gear profile when the torque sleeve is in the second position.

0042In an illustrative example not forming any part of the protected scope, the first position of the torque sleeve is a raised position, and the second position of the torque sleeve is a lowered position.

0043In an illustrative example not forming any part of the protected scope, the drive stem comprises a drive gear profile engagable with the motor.

0044In an illustrative example not forming any part of the protected scope, the drive stem extends through an interior of the torque sleeve.

0045In an illustrative example not forming any part of the protected scope, the drive unit also includes a swivel co-axial with the drive stem.

0046In an illustrative example not forming any part of the protected scope, the swivel is a hydraulic swivel.

0047In an illustrative example not forming any part of the protected scope, the drive unit also includes an actuator configured to move the torque sleeve between the first position and the second position.

0048In an illustrative example not forming any part of the protected scope, the actuator is a hydraulic cylinder.

0049In an illustrative example not forming any part of the protected scope, the top drive system also includes a tool adapter having a complementary load coupling to the load coupling of the drive stem, and a stem gear profile that is complementary to the sleeve gear profile.

0050In an illustrative example not forming any part of the protected scope, the top drive system also includes at least one coupling between the drive unit and the tool adapter selected from a group consisting of: threaded couplings, hydraulic couplings, pneumatic couplings, electronic couplings, fiber optic couplings, power couplings, data couplings, signal couplings, bi-directional torque couplings, axial load couplings, power couplings, data couplings, and signal couplings.

0051In an illustrative example not forming any part of the protected scope, a method of coupling a drive unit to a tool adapter includes positioning the tool adapter below the drive unit; rotating a drive stem of the drive unit to make up a threaded coupling with a tool stem of the tool adapter; and moving a torque sleeve of the drive unit to engage both a torque gear profile of the drive stem and a stem gear profile of the tool stem.

0052In an illustrative example not forming any part of the protected scope, moving the torque sleeve comprises moving the torque sleeve from a raised position to a lowered position.

0053In an illustrative example not forming any part of the protected scope, the method also includes forming a coupling between the drive unit and the tool adapter, wherein the coupling is selected from a group consisting of: threaded couplings, hydraulic couplings, pneumatic couplings, electronic couplings, fiber optic couplings, power couplings, data couplings, signal couplings, bi-directional torque couplings, axial load couplings, power couplings, data couplings, and signal couplings.

0054In an illustrative example not forming any part of the protected scope, the method also includes transferring torque from the drive stem through the torque sleeve to the tool stem.

0055In an illustrative example not forming any part of the protected scope, the method also includes transferring axial load with the threaded coupling between the drive stem and the tool stem.

0056In an illustrative example not forming any part of the protected scope, a drive unit of a top drive system includes a drive stem having a load coupling that is a threaded coupling; a spindle unit comprising: an interior through which the drive stem extends; a counter nut having a first guide profile mated with a second guide profile on the drive stem; and a spindle having threading mated with threading on the counter nut; and an annular motor operationally coupled to the spindle unit.

0057In an illustrative example not forming any part of the protected scope, the annular motor comprises a fixed portion that is fixed to the drive stem and a rotatable portion that is rotatable relative to the drive stem.

0058In an illustrative example not forming any part of the protected scope, the rotatable portion is rotationally coupled to the spindle.

0059In an illustrative example not forming any part of the protected scope, the first guide profile is on an interior surface of the counter nut and the threading is on an exterior surface of the counter nut.

0060In an illustrative example not forming any part of the protected scope, the drive unit also includes a motor, wherein the drive stem comprises a drive gear profile engagable with the motor.

0061In an illustrative example not forming any part of the protected scope, at least a portion of the annular motor is fixed relative to the drive stem.

0062In an illustrative example not forming any part of the protected scope, the top drive system also includes a tool adapter having a complementary load coupling to the load coupling of the drive stem, and a shoulder proximate a top of the tool adapter.

0063In an illustrative example not forming any part of the protected scope, the top drive system also includes at least one coupling between the drive unit and the tool adapter selected from a group consisting of: threaded couplings, hydraulic couplings, pneumatic couplings, electronic couplings, fiber optic couplings, power couplings, data couplings, signal couplings, bi-directional torque couplings, axial load couplings, power couplings, data couplings, and signal couplings.

0064In an illustrative example not forming any part of the protected scope, a method of coupling a drive unit to a tool adapter includes positioning the tool adapter below the drive unit; rotating a drive stem of the drive unit to make up a threaded coupling with a tool stem of the tool adapter; and rotating a spindle unit relative to the drive stem to contact a counter nut of the spindle unit with the tool stem.

0065In an illustrative example not forming any part of the protected scope, the spindle unit remains fixed relative to the drive stem while rotating the drive stem to make up the threaded coupling.

0066In an illustrative example not forming any part of the protected scope, rotating the spindle unit relative to the drive stem moves the counter nut vertically relative to the drive stem.

0067In an illustrative example not forming any part of the protected scope, the method also includes forming a coupling between the drive unit and the tool adapter, wherein the coupling is selected from a group consisting of: threaded couplings, hydraulic couplings, pneumatic couplings, electronic couplings, fiber optic couplings, power couplings, data couplings, signal couplings, bi-directional torque couplings, axial load couplings, power couplings, data couplings, and signal couplings.

0068In an illustrative example not forming any part of the protected scope, the method also includes transferring bi-directional torque with the threaded coupling between the drive stem and the tool stem.

0069In an illustrative example not forming any part of the protected scope, the method also includes transferring axial load with the threaded coupling between the drive stem and the tool stem.

0070In an embodiment, a drive unit of a top drive system includes a drive stem having first friction surfaces and a load coupling, wherein the load coupling is a threaded coupling; a transmission unit having: second friction surfaces parallel to the first friction surfaces; and shoulders proximate a bottom of the transmission unit; and a transmission selector movable to an "on" position or an "off" position, wherein the drive stem moves synchronously with the transmission unit when the transmission selector is in the "on" position.

0071In one or more embodiments disclosed herein, the drive unit also includes a swivel selector movable to an "on" position or an "off" position, wherein the transmission unit moves synchronously with a swivel of the drive unit when the swivel selector is in the "on" position.

0072In one or more embodiments disclosed herein, the swivel comprises a stationary portion and a rotatable portion, and the swivel selector couples to the stationary portion.

0073In one or more embodiments disclosed herein, the drive unit also includes a selection ring that includes the transmission selector.

0074In one or more embodiments disclosed herein, the selection ring comprises coupling pins, and the transmission unit comprises coupling holes engagable with the coupling pins.

0075In one or more embodiments disclosed herein, the first friction surfaces are top and bottom surfaces of disks projecting radially outward on the drive stem, and the second friction surfaces are top and bottom surfaces of annular disks encircling the drive stem.

0076In one or more embodiments disclosed herein, the top drive system also includes a tool adapter having a complementary load coupling to the load coupling of the drive stem, and shoulders complementary to those of the transmission unit.

0077In one or more embodiments disclosed herein, the top drive system also includes at least one coupling between the drive unit and the tool adapter selected from a group consisting of: threaded couplings, hydraulic couplings, pneumatic couplings, electronic couplings, fiber optic couplings, power couplings, data couplings, signal couplings, bi-directional torque couplings, axial load couplings, power couplings, data couplings, and signal couplings.

0078In one or more embodiments disclosed herein, the shoulders of the transmission unit are on an interior surface of the transmission unit, and the shoulders of the tool adapter are on an exterior surface of a tool stem of the tool adapter.

0079In an embodiment, a method of coupling a drive unit to a tool adapter includes positioning the tool adapter below the drive unit so that shoulders of a transmission unit of the drive unit align with shoulders of a tool stem of the tool adapter; and rotating a drive stem of the drive unit to make up a threaded coupling with the tool stem, wherein: the drive stem and the transmission unit rotate together during the positioning of the tool adapter; and the drive stem and the transmission unit do not rotate together during the making up of the threaded coupling.

0080In one or more embodiments disclosed herein, the method also includes, before making up the threaded coupling, moving a swivel selector to an "on" position to rotationally couple the transmission unit with a housing of the drive unit.

0081In one or more embodiments disclosed herein, the method also includes rotating a portion of a swivel relative to the housing to wrench the threaded coupling.

0082In one or more embodiments disclosed herein, the method also includes, after making up the threaded coupling, moving a transmission selector to an "on" position.

0083In one or more embodiments disclosed herein, the method also includes, after moving the transmission selector to the "on" position, moving a swivel selector to an "off" position.

0084In one or more embodiments disclosed herein, the method also includes forming a coupling between the drive unit and the tool adapter, wherein the coupling is selected from a group consisting of: threaded couplings, hydraulic couplings, pneumatic couplings, electronic couplings, fiber optic couplings, power couplings, data couplings, signal couplings, bi-directional torque couplings, axial load couplings, power couplings, data couplings, and signal couplings.

0085In one or more embodiments disclosed herein, the method also includes transferring torque from the drive stem to the transmission unit through frictional surfaces.

0086In one or more embodiments disclosed herein, the method also includes mating the shoulders of the transmission unit with the shoulders of the tool stem to transfer torque from the drive stem to the tool stem.

0087In one or more embodiments disclosed herein, the method also includes transferring axial load with the threaded coupling between the drive stem and the tool stem.

0088While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.