The invention relates to an apparatus for making up and breaking out a threaded connection in a subs assembly connected to the driveshaft of a top-drive drilling machine, in which, in a position of application, a main frame is fixed in a rotationally rigid manner to and projects up from a base, the main frame is provided with a through centre opening arranged to receive the subs assembly, and a first clamping device, which, by releasable abutment against a portion of the subs assembly, is arranged to hold the subs assembly fixed in the centre opening, is arranged in an upper portion of the main frame. A method for replacing at least part of a subs assembly on the driveshaft of a top-drive drilling machine is described as well.

When a top-drive drilling machine is used, for example in exploration and production drilling for oil and gas, one or more subs with varying functions are arranged between the driveshaft and the drill string. A sub may function solely as a replaceable wear part for the threads of the driveshaft not to become ruined by constantly being connected and disconnected. Such a sub may stay connected to the driveshaft until it must be replaced because of wear. Another type of sub may include safety valves for controlling the fluid pressure in the drill string, typically one or more so-called IBOPs (Internal Blowout Preventers). Such a sub must be disassembled regularly for a required valve check. Because of adjacent elements, for example frame details, ordinary pipe tongs which are used for making up and breaking out pipe sections have a reach which makes it impossible for them to be used to remove and fit said subs, as the drilling machine will hit the tongs before the jaws of the tongs encircle the sub. For the removal and fitting of subs of this kind it is therefore common to position a separate pair of rigging tongs provisionally around the sub, for instance by means of a lifting device (a winch or the like) and a stack of pallets. This work involves a great risk of injury to personnel, and the operation is time-consuming and thereby expensive, as the drilling will have to be stopped for this period.

The applicant's own NO patent 333414 discloses a tool for mounting a subs assembly on the driveshaft of a top-drive drilling machine, in which, by releasable abutment against a portion of the subs assembly, a pair of tongs arranged to hold the subs assembly fixed is arranged on an upper portion of a frame which, in a position of application, is fixed in a rotationally rigid manner to and projects from a base, the frame being provided with a through centre opening arranged to receive a substantial portion of the subs assembly, characterized by the centre opening extending, in the position of application of the main frame, through an opening in the base. The drawback of this solution is that a connected top-drive drilling machine will have to be put in operation to break out the subs assembly, which is to be replaced, from the driveshaft of the drilling machine.

US 7367402 Bl discloses a tool for assembling and disassembling pipes, in which a housing formed of a tubular base section may be fixed to a rotary table, for example, a torque-generating section is arranged above the base section, and a gripping section is attached to the torque-generating section. The tool has a centre opening extending through it.

US 6276450 Bl discloses an apparatus for rapid replacement of an IBOP in a top drive system by means of a pair of pipe tongs, a rotary-table element and a drive ring arranged to transmit torque from a top-drive drilling machine to the rotary table.

The invention has for its object to remedy or reduce at least one of the drawbacks of the prior art or at least provide a useful alternative to the prior art.

The object is achieved through the features, which are specified in the description below and in the claims that follow.

An apparatus arranged to be fixed at a drilling floor, preferably on a lockable rotary table, is provided, there being a rotationally rigid main frame projecting up from a foundation provided with means arranged to fix the apparatus to the drilling floor. The main frame includes a through centre opening which is arranged to receive a subs assembly and which is provided, at a lower portion, with an abutment arranged to support the subs assembly. The main frame is preferably tubular. The main frame advantageously extends through the foundation, as a portion projecting downwards is arranged to extend down through an opening in the drilling floor, for example down through a centre opening in the rotary table.

In a portion near the upper end portion of the main frame, a first clamping device is arranged, provided with jaws arranged to rest against the subs assembly when this has been inserted into the centre opening of the main frame. The clamping device preferably includes several linear actuators, for example hydraulic cylinders, which are evenly spaced around the main frame and may be provided with replaceable jaws for optimum adaptation to the subs assembly which is to be held fixed in the apparatus.

The apparatus is also provided with a second clamping device arranged to be rotatable over a sector around the centre axis of the main frame. The second clamping device is preferably arranged in a rotary frame, which is supported in an upper portion of the main frame, and preferably includes several linear actuators, for example hydraulic cylinders, which are evenly spaced around the main frame and may be provided with replaceable jaws for optimum adaptation to the subs assembly which is to be held fixed in the apparatus. The rotary motion of the rotary frame, which is typically restricted to a sector of up to 30°, is provided by one or more rotation actuators, for example one or more linear actuators connecting an outer portion of the rotary frame to a projecting portion of the main frame. Other forms of actuators can be used as well to provide rotation of the rotary frame, for example one or more rotation actuators, typically one or more hydraulic motors, which are fixed to one of the rotary frame and the main frame and, with gears, is/are in engagement with a toothed rim arranged on the other one of the rotary frame and the main frame. Because of the need for a great torque, especially when the connections in the subs assembly are to be broken out, linear actuators in the form of hydraulic cylinders are preferred.

The invention is defined by the independent claims. The dependent claims define advantageous embodiments of the invention.

In a first aspect, the invention relates more specifically to an apparatus for making up and breaking out a threaded connection in a subs assembly connected to the driveshaft of a top-drive drilling machine, in which

in a position of application, a main frame is rotationally rigidly fixed to and projects up from a base,

the main frame is provided with a centre opening arranged to receive the subs assembly, and

a first clamping device, which, by releasable abutment against a portion of the subs assembly, is arranged to hold the subs assembly fixed in the centre opening, is arranged in an upper portion of the main frame,

characterized by

a second clamping device being arranged at a distance from the first clamping device, rotatable over a sector around the centre axis in the centre opening of the main frame. In the position of application of the apparatus, the rotatable, second clamping device may be arranged closer to the drilling machine than the first clamping device. It is an advantage if the rotary motion can be observed by the operator of the tool.

The second clamping device may be arranged in a rotary frame, which is supported in the main frame, and includes at least one rotation actuator forming a movable connection between the main frame and the rotary frame. The movable connection may, more particularly, be formed by an outer portion of the rotary frame and a projecting portion of the main frame being interconnected by means of a linear actuator.

The size of the sector may be up to 40°, alternatively up to 30°, alternatively up to 20°. An advantage of this is that the rotatable, second clamping device has a work range which makes it possible to use rotation actuators having relatively small dimensions and providing a great torque.

The axial distance between the first clamping device and the second clamping device may be large enough for said clamping devices each to be brought into releasable abutment against a respective one of successive elements in the subs assembly, possibly against a respective one of a first sub in an upper end portion of the subs assembly and a portion of the driveshaft of the drilling machine.

In its longitudinal direction and remotely from the first clamping device, the centre opening may be defined by a bottom abutment. There is thereby no risk of a loosened subs assembly or parts thereof falling through openings in the base below the tool, for example through a rotary table in a drilling floor.

The main frame may be formed as a telescopic tubular body. The tool may thereby easily be adapted to subs assemblies of different types.

In a second aspect, the invention relates more specifically to a method for replacing at least part of a subs assembly on the driveshaft of a top-drive drilling machine, the method including the following steps:

a) fixing an apparatus as described above to a base, the vertically arranged centre axis of the apparatus being within the working area of the drilling machine;

b) lowering the drilling machine until a portion of the subs assembly has been inserted into a centre opening in the apparatus;

c) moving the one of a first clamping device and a second clamping device that is the closer to the driveshaft of the drilling machine into fixing abutment against a portion of the subs assembly or against a portion of the driveshaft;

d) moving the other one of the first clamping device and the second clamping de- vice into fixing abutment against an adjacent portion of the subs assembly;

e) rotating the second clamping device over a sector to loosen the respective, fixed driveshaft or portion of the subs assembly;

f) releasing the one of the first clamping device and the second clamping device that is the closer to the driveshaft of the drilling machine from the fixed portion of the subs assembly or the fixed driveshaft;

g) rotating the driveshaft of the drilling machine until the connection between the subs assembly and the driveshaft, possibly the loosened portion of the subs assembly and the remaining portion(s) of the subs assembly, has ceased to exist;

h) pulling the drilling machine away from the tool; and

i) releasing the other one of the first clamping device and the second clamping device from the adjacent portion of the subs assembly and removing the subs assembly from the tool.

In what follows, an example of a preferred embodiment is described, which is visualized in the accompanying drawings, in which :

Figure 1 shows a perspective drawing of the tool according to the invention;

Figure 2 shows a side view, on a smaller scale, of the tool and a top-drive drilling machine;

Figure 3 shows a plan view, on a larger scale, of the tool; Figure 4 shows a radial section IV-IV through the tool; and Figure 5 shows an axial section V-V through the tool.

In the figures, the reference numeral 1 indicates a tool according to the invention. A base for the tool 1 in an operative position is formed of a drilling floor 2, and a top- drive drilling machine 3 is displaceably arranged in a rig (not shown) extending up from the drilling floor 2, see figure 2.

The drilling floor 2 is provided with a rotary table 21 known per se with a centre opening 211.

The drilling machine 3 is provided with a driveshaft 31 with an end portion projecting downwards, arranged for releasable connection to a subs assembly 32 constructed from several elements mutually screwed together. In the example shown, the subs assembly 32 includes elements like a first intermediate sub 321, first and second internal blowout preventers (IBOPs) 322, 323 and a wear sub 324, but the subs assem- bly 32, which remains connected to the drilling machine 3 during repeated make-ups of pipe sections (not shown) in a drill string (not shown), possibly repeated break-outs of pipe sections (not shown) from a drill string (not shown), may exhibit a wide range of designs. Said first intermediate sub 321 and wear sub 324 have for their main purpose to provide inexpensive, easily replaceable components that spare threaded portions on the driveshaft 31 and on IBOPs 322, 323 from heavy wear due to frequent make-ups and break-outs.

Reference is now made especially to figures 3, 4 and 5. In an upper portion 131 of the main frame 13, the tool 1 is provided with a first clamping device 11 formed of two first linear actuators, typically hydraulic cylinders which are arranged radially opposite, and are provided with jaws 112 arranged around a centre opening 135 extending through the main frame 13. In an operative state, the first clamping device 11 is connected to a hydraulic plant (not shown). The first clamping device 11 is arranged in a rotationally rigid manner around the centre axis in the centre opening 135 of the main frame 13.

A second clamping device 12, substantially of the same design as the first clamping device 11, is arranged in a rotary frame 121, which is arranged to be rotatable around the upper portion 131 of the main frame 13 above the first clamping device 11. Two opposite outer rotary-frame portions 121a located remotely from said centre opening 135 are connected to respective frame portions 131a, which project diametrically out from the main frame 13, by means of rotation actuators in the form of linear actuators 124, typically hydraulic cylinders. The rotation actuators 124 are arranged to rotate the rotary frame 12 and the associated second clamping device 12 over a sector S around the centre axis of the main frame 13.

In an operative state, the centre axis in the centre opening 135 extending through the main frame 13 is arranged perpendicularly to the base 2. In the exemplary embodiment shown, the main frame 13 is formed as a telescopic pipe, but a wide range of embodiments, which provide forms that give sufficient support to the clamping devices 11, 12 and hold the loosened subs assembly 32 in position can be used.

The main frame 13 is provided with a foundation 133, which includes attachment means 134 arranged to be in rotationally rigid engagement with a portion at an opening in the base 2, typically around the centre opening 211 of the rotary table 21.

In the centre opening 135, an abutment 136 is arranged in the lower frame portion 132, arranged to support the subs assembly 32 when this has been disconnected from the driveshaft 31 and the clamping devices 11, 12. The abutment 136 may be adjustable in the longitudinal direction of the centre opening 135, and the abutment 136 may be dampingly connected to the main frame 13. In this connection, reference is made to the applicant's own NO patent 333414.

The tool 1 is used especially when a subs assembly 32 is to be broken out into its single elements 321-324 or disconnected in its entirety from the driveshaft 31 of the drilling machine 3. The subs assembly 32 is lowered into the centre opening 135 so that the first clamping device 11 can be brought into abutment against a portion of the subs assembly 32, that is to say a sub element 321, 322, 323 or 324. The second clamping device 12, which, for breaking-out purposes, has been rotated back into its initial position, as is shown in the figures, is brought into abutment against the sub element 321, 322 or 323, possibly against a portion of the driveshaft 31 if the entire subs assembly 32 is to be broken out from the drilling machine 3. Then the second clamping device 12 is rotated over the sector S so that the relevant threaded connection is broken out. During the break-out, the driveshaft of the drilling machine 3 is rotatable, at least over a sector corresponding to the rotation sector S of the second clamping device. After the threaded connection has been broken out, the second clamping device 12 is withdrawn, so that the sub element 321, 322 or 323 held fixed, possibly the driveshaft 31, is rotatable, and the drilling machine 3 is set in operation so that the driveshaft 31 completely unscrews the relevant threaded connection. In this way, placing the strain of the actual break-out on the drilling machine 3 is avoided, and the short axial distance between the clamping devices 11, 12 makes it possible to separate sub elements with a very short building length. It has turned out that a relative rotation over a sector size S of down towards 5° may be sufficient to break out the threaded connection so much that the further unscrewing gives no risk of overstressing the drilling machine 3.

Even though the properties of the tool 1 are particularly beneficial in breaking out threaded connections in connection with subs assemblies 32, the tool 1 may also be used when making up such threaded connections, by the processes that have been described above being reversed.

It should be noted that all the above-mentioned embodiments illustrate the invention, but do not limit it, and persons skilled in the art may construct many alternative embodiments without departing from the scope of the dependent claims. In the claims, reference numbers in brackets are not to be regarded as restrictive. The use of the verb "to comprise" and its different forms does not exclude the presence of elements or steps that are not mentioned in the claims. The indefinite article "a" or "an" before an element does not exclude the presence of several such elements..