NO20131209A1 - A method and a device for assembling or dismantling a structure under water - Google Patents

Abstract

The invention relates to a method for carrying out an underwater operation on a structure (10) or in the vicinity of the structure, the method comprising: - providing a device (18) comprising a movable arm (20), the device being designed to perform an underwater operation on the structure or near a structure, the device comprising: * at least a first support (22) designed to be connected to the structure, the support configured to transmit essential forces in three dimensions and significant moments about X -axis, Y-axis and Z-axis of the movable arm of the structure, including a vertical force required to lift the device, * at least a first articulated, movable arm (20) directly or indirectly attached to a proximal end (34) of said support, wherein the first movable arm comprises a first tool (30) attached to a distal end (36) of said first movement arm, wherein the first tool (30) is movable in a three-dimensional working area (98) around at least the first support, * at least one actuator (33) configured to controllably move the first tool (30) in the three-dimensional working area to positioning the first tool at a target location, * a control device (56) configured to control the at least one actuator and the tool during operation, - attaching the device to the structure via the at least one support, - moving the tool into three dimensions and performing an operation underwater. .

Description

Reference

This patent application claims priority from NL2006153, filed 7/2/2011 entitled “Method and device for assembling and disassembling a structure under water” and from US provisional application 61/440,127, filed 7/2/2011, with the same title, where these applications are incorporated herein by reference.

Field of the invention

The present invention relates to a method and a device for assembling and dismantling a structure which is at least partially submerged, in particular for dismantling a jacket structure.

Background for the invention

In the offshore industry, jacket structures (or just jackets) are often used to support and fix platforms above the sea surface. A jacket structure is generally positioned directly on the seabed. A jacket comprises many tubes which are connected together and form a lattice structure. The beams are generally made of steel. A jacket generally comprises a number of beams which are essentially vertical and which extend from a base of the jacket to the top of the jacket. The upright beams are generally connected to each other via horizontal and vertical cross beams.

When a jacket reaches the end of its economic and technical life it may have to be removed. The necessary removal depends on local, administrative orders and can be partial or complete.

In a known method for removing a jacket, a vessel with a large lifting capacity is used to support a top part of the jacket. The jacket is then cut a certain distance above the seabed. The section above the cut-through is lifted and removed with the heavy-lift vessel, and the section below the cut-through remains in place. A further cutting and lifting operation may be required to remove the next section.

Cutting the jacket is generally a time-consuming and expensive operation. In general, a large vessel with a crew is required to be able to carry out the cutting. Divers or one or more ROVs and special cutting and lifting equipment are required for the actual cutting. For the lifting operation, heavy lifting capacity is required, which is expensive.

The known removal operation has a further disadvantage in that bad weather can cause significant delays, which further increases costs.

In the field, there is a need for a more efficient and cost-effective way of removing jacket structures.

Purpose of the invention

It is an aim of the present invention to provide a method and device for reliably and efficiently removing a large jacket structure which is at least partially submerged.

Summary of the invention

The invention provides a method for performing an underwater operation on a structure (10) or in the vicinity of the structure, where the method comprises: providing a device (18) comprising a movable arm (20), where the device is designed to perform an underwater operation on the structure or in the vicinity of a structure, wherein the device comprises:<*>at least a first support (22) which is designed to be connected to the structure, where the support is configured to transmit significant forces in three dimensions and significant moments about the X-axis, Y-axis and Z-axis from the movable arm of the structure, including a vertical force necessary for lifting operations of the device,<*>at least one first joint, movable arm (20) directly or indirectly attached to a proximal end (34) of said support, wherein the first movable arm comprises a first tool (30) attached to a distal end (36) of said first movable arm, wherein the first tool ( 30) is movable in a three-dimensional working area (98) around at least the first support,<*>at least one actuator (33) configured to controllably move the first tool (30) in the three-dimensional working area to position controlling the first tool at a target location,<*>a controller (56) configured to control the at least one actuator and the tool during operation,

attach the device to the structure via the at least one support,

move the tool in three dimensions and carry out an operation underwater, where forces and moments arising during the operation are transferred to the structure.

With the method according to the invention, underwater operations on a structure or in the vicinity of a structure are possible.

In one embodiment, all forces necessary for the operation are transferred to the structure.

In one embodiment, the invention provides a method for assembling or disassembling a structure that is located at least partially underwater, where the method comprises:

Provide a device comprising at least one movable arm, where:

• the movable arm comprises at least a first segment and a second segment connected to each other via at least a first hinge, • the support is connected to a proximal end of the first segment via at least one support hinge, where the support is designed to be mounted on the structure,

• the tool is mounted on a distal end of the second segment,

• the at least one actuator is configured to:

o controllably move the first segment relative to the support to

to support, and to

o controllably move the second segment relative to the first segment to position the tool at a target location in a working area of the arm,

the control device is configured to control the at least one actuator and the tool during operation,

perform a processing operation on the structure to assemble or

dismantle the structure.

With the present invention, a large jacket structure can be dismantled. It is possible to dismantle a jacket structure on e.g. 100 meters. The disassembly operation can be performed substantially independently by the movable arm. The movable arm may be connected to one or more umbilicals which provide electrical and/or hydraulic power, communication cables, fiber optics and the like. The umbilical can extend to a vessel on the surface of the water or straight to land.

It is also possible to dismantle the lower part of the jacket after the top part has been removed in a heavy lifting operation. The invention can also be used to dismantle large objects resting on the seabed as a result of an accident, e.g. a sunken ship. The movable arm has a substantial lifting capacity, ie, 10 tons or more. This is necessary to handle large tools and jacket segments. The movable arm thus does not need an additional underwater balloon to provide additional lifting capacity.

Underwater cranes are known for other purposes. US 4109480 discloses a submarine "cherry picker" designed to be positioned on the seabed and suitable for repairing an underwater pipeline. This "cherry-picker" is not suitable for dismantling a jacket structure, at least because the working area above the seabed is too limited. The "cherry picker" also lacks sufficient lifting capacity to be able to handle parts without an additional balloon. Furthermore, the cherry-picker according to US4109480 is limited to lifting parts, and cannot perform any functionality other than lifting because only a hook 65 is provided at the end of the crane.

US6267037 B1 describes a cutting tool for cutting an underwater pipeline. The tool includes a cutting wire that is rotated to cut the pipeline. The tool has limited capabilities and is not very versatile. A part that is cut off from the structure is uncontrolled and falls to the seabed. The apparatus in US6267037 B1 is therefore not suitable for dismantling a jacket independently or substantially independently.

In one embodiment, the tool comprises a gripping tool.

In another embodiment, the tool comprises a gripping tool selected from the group comprising:

a cutting tool to cut into the structure,

an excavating device for digging on the seabed to collect material which

lies on the seabed,

a drilling device for drilling a hole in the structure, and/or a sampling device for taking a sample, in particular from the structure, from

the seabed or from the water.

In one embodiment, the method comprises:

grab part of the structure with the grab tool,

cut into the structure with the cutting tool so that said part is separated from

the structure,

move the separated part away from the structure with the gripper tool.

In this way, the part can be moved in a simple and efficient way.

In one embodiment, the method comprises simultaneously gripping the part with the gripping tool and cutting with the cutting tool, thereby preventing the part from falling when the part is separated from the structure. The ability to simultaneously grip in one place and cut in another location enables safe removal of the parts, without dropping the parts to the seabed below.

In one embodiment, the cutting tool is movable relative to the gripping tool, which enables a part of the structure to be held with the gripping tool while the cutting tool cuts the structure at various positions necessary to separate the part from the structure, where the method comprises: - gripping a part of the structure which to be separated from the structure with the gripping tool, - move the cutting tool to different locations and cut into the structure at the various locations to separate the part from the structure, while maintaining the grip on the part with the gripping tool.

Generally, a part such as a beam is attached to the rest of the structure in several places. Generally, multiple cuts will be made to completely separate the part from the structure. Because the cutting tool is movable relative to the gripping tool, a part of significant size can be separated from the structure. In one embodiment, the working area of the cutting tool extends up to 5 meters from the gripping tool. In this way, up to 10 meters can be removed from the structure.

In one embodiment, the method comprises:

- providing a container on the seabed within a working area of the movable arm,

- each time separate a part from the structure,

- place the separated parts in the container with the arm,

lift the filled container to the surface of the water,

transport the container to a remote location with a vessel.

The parts can be suitably collected in the container. Litter with parts on the seabed can be avoided, leading to a clean removal operation. The container can be hoisted up with a cable by a vessel. A new, empty container can be put in place before the full container is removed to ensure that the operation does not stop.

In one embodiment, the support comprises at least one clamp, where the method comprises:

- clamp the structure in a first position,

- remove at least one first part from the structure, and in particular as many parts as are within the working area of the movable arm at the first position,

- release at least one clamp,

- move the support to a second position on the structure and clamp the structure at the second position, - remove at least one part from the structure, and specifically as many parts as are within the working range of the movable arm at the second position,

repeat these steps until the structure is, so to speak, dismantled.

By starting at the top of the structure and moving downwards, an efficient operation is possible. In the case of a jacket that is further than the working area of the movable arm, it is possible for the movable arm to be positioned in several places in one horizontal level before being moved down to a next, lower horizontal level.

In one embodiment, the movable arm is moved in a downward spiral along the outer side of the structure to dismantle the structure.

In one embodiment, the method comprises clamping the at least one clamp on a vertical beam or essentially vertical beam on the structure and moving down said beam from said first position to said second position and further down until the structure is, so to speak, dismantled.

The substantially vertical beam is a suitable location for supporting the movable arm and may act as a rail along which the support may move downwardly.

In one embodiment, an additional rail is mounted on the support structure to support the arm, wherein the support on the movable arm is designed to contact said rail and slide or roll along said rail. The rail has a vertical or so to speak vertical orientation. The rail may be mounted on the vertical or so-called vertical beam and extend substantially parallel to the vertical or so-called vertical beam.

In one embodiment, the control device comprises cameras.

In one embodiment, the control device includes:

- a data processing device comprising a memory configured to store: • geometric data relating to the original shape of the structure, and • disassembly data relating to the progress of dismantling the structure and the current shape of the structure. - one or more sensors designed to determine a current position of the arm and tool relative to the structure, and wherein the method comprises:

- load the geometric data into the memory,

- determine a part to be removed from the structure and determine a target position for the tool based on the geometric data and the disassembly data,

move the tool to the target position,

- remove a part from the structure by grasping the part, cutting into the structure until the part is separated and moving the part away from the structure,

- update the disassembly data with data about the removed part,

- repeat the steps until the structure is dismantled.

With this embodiment, feedforward and feedback control can be combined for an efficient removal process. With the geometric data and the disassembly data, a next part to be removed can be determined. It can also be determined how the movable arm can reach said part. If the support needs the movable arm to be repositioned to another support location, this can be carried out before the cutting operation. The support may need to be repositioned vertically or horizontally. Then the part is grabbed and the structure is cut in. Then the part is removed and the disassembly data is updated with the removed part.

The sensors provide data for precise positioning. Although the complete shape of the structure is theoretically known from the geometric data, obstacles may exist due to an incomplete or inaccurate drawing. With the sensors, the actual data can be used for precise positioning.

In one embodiment, the method comprises:

- cut the structure at a cutting point, where a top part of the structure is separated from a bottom part of the structure, - lift the top part of the structure with a lifting device on a vessel and remove the top part from the localization with the vessel, - dismantle the bottom part of the structure in accordance with the procedure according to requirements 1.

In some situations, it is more efficient to remove a top part from the jacket with a lifting operation. Only the bottom part then needs to be dismantled with the movable arm. This will speed up the overall dismantling time and will allow the moving arm to work at a depth below the water surface where there is no wave action.

In one embodiment, the method comprises:

- providing a first of said movable arms,

- providing another of said movable arms,

- grasp a part of the structure with the gripping tool on the first movable arm, - cut into the structure with the cutting tool on the second movable arm so that said part is separated from the structure, - move the separated part away from the structure with the first movable arm.

With a pair of arms it is possible to increase the speed of the operation. Furthermore, it may be necessary to support some parts in more than one place. This can be done with two or more arms.

In one embodiment, the method comprises:

- grip the first movable arm with the gripping tool on the second movable arm,

- release the support of the first movable arm from the structure,

- moving the first movable arm with the second movable arm so that the support of the first movable arm is moved from a first support position to a second support position, thereby changing the working area of the first movable arm.

One arm can be used to effectively reposition another arm. This makes it possible to easily reposition the arms.

In one embodiment, the method comprises:

- providing a device comprising a movable arm, where the device further comprises: • a body, where the first articulated arm is connected to the at least one support via said body, where the first movable arm comprises a gripping tool, • a second articulated, movable arm directly or indirectly connected on a proximal end to said support, where the second movable arm comprises a processing tool connected to a distal end of said second movable arm, where the processing tool is movable in a three-dimensional working area around at least the first support, - perform a processing operation on the structure with the grab tool and the process tool.

In one embodiment, the method comprises:

- providing a device, in which on both the proximal end and the distal end of the articulated movable arm there is provided:

• a support, and

• a processing tool,

wherein the proximal end and the distal end are configured to switch functions, - in a first mode of operation, mounting the support on the proximal end of the structure and performing a processing operation with the processing tool on the distal end, and - in a second mode of operation, mounting the support on the distal end of the structure and perform a processing operation with the processing tool on the proximal end.

In one embodiment, the method comprises: providing a vessel above the structure and assisting the operation by attaching a line from the vessel to the articulated movable arm or to a portion of the structure and exerting an upwardly directed force on the articulated movable arm or portion of the structure via the line.

In one embodiment, the method includes providing at least one submerged buoyancy tank and assisting the operation by attaching a line from the buoyancy tank to the articulated movable arm or to a portion of the structure and exerting an upwardly directed force on the articulated movable arm or portion of the structure via the line.

In one embodiment, the method comprises connecting a digging device to the distal end of the at least one articulated movable arm and performing at least one digging operation in the vicinity of the structure.

The present invention relates to a method for assembling or disassembling a structure which is located at least partially underwater, where the method comprises: providing a device which comprises at least one movable arm, where the device comprises: • at least one movable arm comprising at least a first segment and a second segment connected to each other via at least a first hinge, • a support attached to a proximal end of the first segment via at least one support hinge, where the support is constructed to be mounted on the structure or placed on the seabed, • a processing tool mounted on a distal end of the second segment,

• at least one actuator configured to:

o controllably move the first segment relative to the support, and to o controllably move the second segment relative to the first segment, to position the processing tool at a target location in a working area of the arm, • control means configured to control the at least one actuator and the processing tool during operation, - perform a processing operation on the structure to assemble or disassemble the structure.

The present invention further relates to a device comprising a movable arm, where the device is designed to carry out an underwater operation on an at least partially submerged structure or in the vicinity of the at least partially submerged structure, where the device comprises: at least a first support constructed to be attached to the structure, where the support is configured to transmit significant forces in three dimensions and significant moments about the X-axis, Y-axis and Z-axis from the movable arm to the structure, including a vertical force necessary for the device's lifting operations,

at least one first articulated movable arm directly or indirectly attached to a proximal end of said support, wherein the first movable arm comprises a first tool attached to a distal end of said first movable arm, wherein the first tool is movable in a three-dimensional working area around at least the initial support,

at least one actuator configured to controllably move the first tool in the three-dimensional workspace to position the tool at a target location;

a control device configured to control the at least one actuator

and the tool during operation.

The present invention further relates to a device comprising a movable arm for dismantling or assembling a structure which at least partially extends underwater, where: - the movable arm comprises at least a first segment and a second segment attached to each other via at least a first hinge, - the support is attached to a proximal end of the first segment via at least one support hinge, where the support is designed to be mounted on the structure or to be located on the seabed,

- the tool is mounted on a distal end of the second segment,

- the at least one actuator is configured to:

• controllably move the first segment relative to the support, and to • controllably move the second segment relative to the first segment to position the processing tool at a target location in a working area of the arm,

the control means is configured to control the at least one actuator and the tool during operation.

The movable arm provides substantially the same advantages as described in connection with the method above.

In one embodiment, the tool comprises:

- a gripping tool for gripping a part of the structure, and/or

- a processing tool to perform a processing operation on the structure or in the vicinity of the structure.

In one embodiment, the gripping tool and/or the processing tool is rotatable about the distal end of the articulated, movable arm about three independent axes, which provides the gripping tool and/or the processing tool with six degrees of freedom relative to the support.

In one embodiment, the processing tool is selected from the group comprising:

a cutting tool to cut into the structure,

a sampling tool for taking a sample, especially from the structure, from

the seabed or from the water

a drilling tool for drilling a hole in the structure, and/or

a digging tool for digging in the seabed or for collecting lying material

on the seabed.

In one embodiment, the cutting tool is movable relative to the gripping tool, allowing a portion of the structure to be held by the gripping tool while the cutting tool cuts the structure at various positions necessary to separate the portion from the structure.

In one embodiment, the cutting tool is connected to the gripping tool or to the movable arm via a movable cutting arm that provides the cutting tool with a working area that extends around the gripping tool.

In one embodiment, the support comprises a clamping device comprising clamping elements designed to be clamped onto a vertical or so to speak vertical beam of the structure. The clamp comprises clamping elements which have, so to speak, vertically extended gripping surfaces.

In one embodiment, the support includes:

- a first hug,

- a second clamp spaced from the first clamp, and

- at least one support beam connecting the first and second clamps to each other, where the first segment is attached to said support beam via the support hinge.

In one embodiment, the control device includes:

a data processing device comprising a memory configured to

store:

• geometric data relating to the shape of the structure,

• assembly data or disassembly data relating to the individual steps of assembling or disassembling the structure, - one or more sensors designed to determine a current position of the arm and tool relative to the structure.

In one embodiment, the device includes:

- a body, where the first articulated movable arm is attached to the at least one support via said body, where a gripping tool is provided on the distal end, - a second articulated movable arm which is directly or indirectly attached on a proximal end to said support, where the second movable arm comprises a processing tool connected to a distal end of said movable arm, where the processing tool is movable in a three-dimensional working area around at least the first support.

In one embodiment, the device comprises a movable arm which comprises:

- a first support connected to the body and comprising at a distal end thereof a clamp for clamping onto the structure or an insert designed to be inserted into the structure to provide a secure connection to the structure, and - a second support which is connected to the body and which on a distal end thereof comprises a clamp for clamping to the structure or an insert designed to be inserted into the structure to provide a secure coupling with the structure.

In one embodiment, the device comprises a movable arm, where the first support comprises a first articulated leg which is connected to the body at a proximal end and which comprises the clamp or insert device at a distal end thereof, and where the second support comprises a second articulated leg which on a proximal end is connected to the body and which on a distal end thereof comprises the clamp or insert device, wherein the first and second legs comprise actuators for moving the first and second clamps in a three-dimensional working area around the body.

In one embodiment, the device comprises an articulated, movable arm, where both the proximal and distal ends of the articulated, movable arm are provided:

- a support, and

- a processing tool,

wherein the proximal end and the distal end are configured to switch functions, wherein: - the support on the proximal end in a first mode of operation is connected to the structure and the processing tool on the distal end is operable to perform a processing operation on the structure, and - the support on the distal end in a second mode of operation is connected to the structure and the processing tool on the proximal end is operable to perform a processing operation.

In one embodiment, the device comprises a movable arm, where the at least one articulated arm comprises a first, a second and a third segment attached to each other via a first and a second hinge.

In one embodiment, the device comprises a movable arm, which further comprises at least one buoyancy device attached to the at least one articulated arm to increase the lifting capacity of the movable arm.

The present invention further relates to a combination of a first device comprising a movable arm according to any of claims 25-40 and a second device comprising a movable arm according to any of claims 25-40.

In one embodiment of the combination, the first device comprises a first coupling part and the second device comprises a second coupling part, where the first and second coupling parts are configured to be connected to each other to form a united movable arm assembly comprising at least two arms.

In one embodiment of the combination, the coupling parts are substantially provided in a central region of the first movable arm and the second movable arm.

The present invention further relates to a set-up for dismantling a structure which at least partially extends underwater, where the set-up includes:

- at least one movable arm according to the invention, and

at least one container to receive the removed parts from the structure.

The present invention relates to a movable arm for dismantling or assembling a structure which at least partially extends underwater, where the movable arm comprises: - at least a first segment and a second segment which are connected to each other via at least a first hinge , - a support connected to a proximal end of the first segment via at least one support hinge, where the support is designed to be mounted on the structure or to be placed on the seabed,

- a processing tool mounted on a distal end of the second segment,

- at least one actuator configured to:

• controllably move the first segment relative to the support, and for

o

a

• controllably moving the second segment relative to the first segment to position the processing tool at a target location in a working area of the arm, - a control device configured to control the at least one actuator and the processing tool during operation.

Brief description of the drawings

The foregoing and other features and advantages of the present invention will be more thoroughly understood from the following, detailed description of exemplary embodiments with reference to the accompanying drawings. Figure IA shows a schematic side representation of the movable arm according to the invention comprising a cutting tool, Figure IB shows a schematic side representation of the movable arm according to the invention comprising a gripping tool, Figure 2A shows an orthogonal representation of an embodiment of the movable arm in a first operational step, Figure 2B shows an orthogonal representation of an embodiment of the movable arm in a next operational step, Figures 3-8 show schematic side representations of respective steps for the method according to the invention, Figure 9 shows a schematic representation seen from above of a further embodiment of the invention, Figure 10 shows a schematic side view of a further embodiment of the invention,

Figure 11 shows a detailed representation of a processing tool,

Figures 12A and 12B show a schematic side view of a jacket with an embodiment of the invention associated with it, Figure 13 shows a schematic side view of a further embodiment of the invention, Figures 14A and 14B show a schematic side view of a further embodiment of the invention. Figure 15 shows a schematic side view of a further embodiment according to the invention. Figure 16 shows a schematic side view of yet another further embodiment according to the invention, Figure 17 shows a schematic side view of a further embodiment of the invention, Figure 18 shows a schematic side view of yet another further embodiment according to the invention, Figure 19 shows a schematic side view of a further embodiment according to the invention, Figure 20 shows a schematic representation of a further embodiment according to the invention, Figure 21 shows a schematic representation of a further embodiment according to the invention.

Detailed description of the figures

In figure IA, a device 18 comprising an articulated, movable arm 20 according to the invention is shown. The movable arm 20 comprises a support 22 which has two clamps 24A, 24B. The two clamps 24A, 24B are connected to the support 22 and to each other via two intermediate beams 26A, 26B which preferably have adjustable length.

The clamps are designed to transfer significant forces in three dimensions and significant moments about the X-axis, Y-axis and Z-axis from the device 18 to the structure 10. In particular, when a lifting operation is performed, a downwardly directed vertical force is exerted by the device 18 via the support 22 on a structure 10. If a current exists in water, horizontal forces will also be transferred via the support 22 to the structure 10.

In one embodiment, the device does not include a support 22 which is configured to rest on the seabed 100. In this embodiment, all forces and moments are transferred to the structure 10.

In one embodiment, the support 22 is designed to be connected to the structure 10 underwater.

The movable arm 20 is mounted on a tower 63. The tower 63 comprises a pivot 61 via which the arm 20 can be rotated relative to the support 22 about the axis of rotation 62.

A proximal end 34 of a first segment 28A is connected to the tower 63 via a hinge 27.

The arm comprises a first segment 28A and a second segment 28B. The first and second segments are connected to each other via a hinge 29. The movable arm may comprise additional segments, i.e., three or four segments.

The movable arm 20 comprises a number of actuators 33 with which the movable arm can be moved. The actuators 33 can be electric or hydraulic. A power cable 35 is provided and extends between the movable arm 20 and an auxiliary vessel to provide power to a motor 31 for the movable arm 20.

A tool 30 is provided on a distal end 36 of the second segment 28B. In one embodiment, the tool 30 comprises a gripping tool 50.1 one embodiment, the tool 30 comprises a processing tool 51, for example a cutting tool 5 IA. The processing tool can also be another type of equipment such as a tool for drilling 5IB, grinding and the like. The cutting tool 51A may be a saw, a flame cutting tool, a welding tool, a laser device, or another type of cutting tool. In one embodiment, the cutting tool includes a wrench for screwing in or unscrewing bolts.

The axis of rotation 62, the hinge 27 and the hinge 29 give the segment 28B three degrees of freedom relative to the support 22.

The tool 30 is rotatable relative to the segment 28B about three independent axes of rotation 80, 81, 82 via a hinge 84. This provides a tool 30 with six degrees of freedom. The six degrees of freedom means that the tool 30 can be positioned at any position within the 3D working area and have any orientation in this position.

The cutting tool 51A is provided with a rotating cutting wire 109.1 use, the rotating cutting wire 109 cuts through steel pipe in a practical manner.

In Figures 2A and 2B, a jacket 10 or other type of structure to be removed comprises a plurality of substantially vertical (or standing) beams 2. The beams can be oriented at an angle of 0-8 degrees in relation to the vertical. The jacket 10 comprises a grid with 4 on 2 standing beams 2. The jacket further comprises horizontal cross beams 4 which go between the standing beams 2 and diagonal beams 6, which also extend out between the diagonal beams. The beams 2, 4, 6 are attached to each other in joints 7 and form a lattice structure.

The jacket 10 can also include channels 9 and other equipment that is mounted on the grid structure.

The jacket 10 shown in figures 2A, 2B is only a part of the original jacket. This is the bottom part and the upper part of the jacket has already been removed, for example via a heavy lifting operation.

In figure IA, the clamps 24A, 24B are designed to be attached to the vertical beams 2.1, so in this respect the clamps comprise clamping elements 23 which have, so to speak, vertically extended gripping surfaces. The gripping surface 23 is rotatable relative to the intermediate beams 26A, 26B so that their gripping surfaces can be aligned with the intermediate beams. This means that the intermediate beams 26A, 26B can be oriented essentially parallel to a standing beam 2 in the jacket. See also figure 4.

In Figure 1B, a gripping tool 50 is attached to the distal end of the second segment 28B. The gripping tool comprises fingers 101 which are movable relative to each other to grip a part of the structure.

The arm 20 can comprise both a gripping tool 50 and a processing tool 51. Alternatively, the arm can comprise only a gripping tool 50, or only a processing tool 51.

In figure 2A, the device 18 is a different embodiment than the device 18 shown in figures la and lb, in the sense that the arm 20 comprises both a gripping tool 50 and a cutting tool 5 IA, and the device 18 comprises a joint where the arm 20 splits into a gripping arm 20A and a processing arm 20B. The processing arm 20B provides the cutting tool 51A with a working area around the gripping tool 50. The movable processing arm 20B is equipped with an actuator so that the cutting tool 51A can be controllably positioned around the gripping tool 50.

The movable arm comprises at least one actuator and the actuator is connected to a control unit 60.

In one embodiment, the control unit 60 comprises a data processing device. The data processing device comprises a memory configured for storing geometric data relating to the original shape of the structure, and the dismantling data relating to the progress in dismantling the structure and the current shape of the structure.

The geometric data can be obtained from measurements or from a data file that was used to design the jacket, an AutoCAD file or equivalent file from another design program.

The disassembly data may comprise a sequence of disassembly operations in accordance with the structure to be disassembled. In the sequence, the structure can be split into separate parts that are to be removed in sequence.

In one embodiment, the device 18 comprising the movable arm 20 comprises several sensors 102 which are used to determine a current position of the movable arm and of the processing tool relative to the structure. These sensors can be ultrasonic sensors, video cameras and/or pressure sensors that register when the moving arm comes into contact with the structure.

Other sensors are also provided, such as a current sensor 104 to measure the current, a weight sensor 103 to measure the weight of the part 32 being lifted.

Method of operation

With reference to Figure 3, the device 18 which comprises the movable arm according to Figures la, lb works in the following way. When a jacket 10 has to be removed, an auxiliary vessel 110 is positioned on the water surface 111 nearby. An ROV 112 which is connected to the auxiliary vessel via an umbilical 114 is used to cut into the jacket 10, to divide the jacket into a bottom part 10A and a top part 10B.

In Figure 4, two devices 18A, 18B comprising movable arms 20A, 20B are then positioned on the jacket 10. The movable arms 20 are positioned on the jacket 10 from the vessel 110, for example by lowering the movable arms 20A, 20B with a hoist system from the vessel. The clamps 24A, 24B are clamped on one of the standing beams 2, see Figure 1. The movable arms 20A, 20B can also start the operation at a position that lies above the water level, but this is less preferred.

One movable arm 20A comprises at least one gripping tool 50, and one movable arm comprises at least one cutting tool 5 IA. In one embodiment, both arms 20A, 20B comprise both a gripping tool 50 and a cutting tool 5 IA.

Two containers 40 are positioned on the seabed 100, within the working area of the movable arms. The containers comprise one or more connectors 41 for connecting a cable to the container 40. The containers comprise a bottom and side walls and are open at the top so that a part can be placed in the container relatively easily.

In Figure 5, a heavy lifting vessel 120 is positioned on the jacket 10. The heavy lifting vessel 120 comprises a crane 122 and lifts the top part 10A of the jacket 10. The bottom part 10B remains standing on the seabed 100.

With reference to figure 6, the movable arms 20A, 20B then start the operation to cut off a part 32 from the jacket 10. The part will generally be a beam 2, 4, 6 or part of a beam, but can also be a joint 7 or a beam in combination with a link 7.

Each part 32 is gripped with a gripping tool 50. The movement of the gripping tool towards the part 32 and the subsequent gripping of the part 32 with the gripping tool can be performed manually or automatically. In the case of manual movement, an operator can sit above the water surface in the auxiliary vessel 110 and control the movement of the movable arm 2 via a link such as a cable 35.

The part 32 is held firmly by the gripping tool 50. While the part 32 is held by the gripping tool 50, the cutting tool 51A cuts an incision 55 in the jacket 2 with the cutting wire 109, so that the part 32 is separated from.

If the operation is performed with a single arm 20, the processing tool 30 comprises a cutting tool 51A which is movable independently of the gripping tool 50 and which has a three-dimensional working area 52 around the gripping tool 50, as indicated in Figures 2a, 2b. While the gripping tool 50 holds the part 32, the cutting tool 51A thus moves to the places where the cuts must be made and cuts there.

If the operation is performed with two arms 20A, 20B as shown in Figures 5 and 6, the arms can cooperate. One arm 20A can hold the part 32 with the gripping tool while the other arm 20B cuts the part.

When the part 32 is released from the jacket 2, the movable arm moves the part 32 away from the jacket. The movable arm moves the part towards the seabed and places the part 32 in the container 40. The gripping tool 50 then releases the part 32. The movable arm 20 then continues with another part 32.

When all the removable parts 32 within the working area of the movable arm 20 have been removed and placed in the container, the movable arm 20 must be positioned again in another position. It is possible to position the movable arm 20 in another place in the same horizontal level. The movable arm 20 can, for example, be repositioned on another standing beam 2 at the same level.

In one embodiment, this repositioning operation is performed with a crane positioned on board the work vessel 110. A cable is attached to the movable arm 20. The clamps 24A, 24B are released from the structure 10 and the movable arm is repositioned at a new location.

In another embodiment, the movable arm 20 has an ability to relocate itself. The movable arm comprises several clamps. Two clamps are shown, 24A, 24B, but more than two are also possible. These clamps are mounted on movable clamp arms 26. Each clamp is mounted on one end of a movable clamp arm.

In another embodiment, two movable arms 20A, 20B are provided. Both movable arms 20 comprise clamps 24A, 24B via which the structure is gripped. A first movable arm can move the second movable arm by gripping the second movable arm with its gripping tool 50. The second movable arm then releases its clamps 24A, 24B from the structure. The first movable arm moves the second movable arm to another location where the clamps of the second movable arm are again clamped onto the structure. The operation can also be performed in reverse, i.e., the second movable arm can move the first movable arm. When the movable arms are operated together, disassembly is thus carried out relatively quickly, and the new positioning of the movable arms is relatively simple.

When all the removable parts 32 within the working area of the movable arm have been removed, the movable arm 20 is lowered to a new, lower position. The movable arm 20 can, for example, be repositioned on the same standing beam, but in a lower position. When the movable arm is repositioned at a lower location, the working area is also lowered and the jacket structure can be further dismantled.

In Figures 7 and 8, a container 40 when it is full is lifted to the surface by a vessel 120 and transported to land. This can be a crane vessel or any other vessel with sufficient lifting capacity to lift the filled containers 40. A crane vessel can also lift the containers from the seabed and place them on a transport barge. An empty container can replace the full container. When the dismantling operation is finished, all the containers 40 are lifted to the surface.

In one embodiment, the processing tool 51 or the gripping tool 50 comprises a hoisting device with a winch. If the jacket is very large, it is not certain that the movable arm is able to position part of the structure on the seabed because the arm is too short and the working area too limited. The removed part can then be lowered to the seabed with the lifting device.

In one embodiment, the movable arm is equipped with rails to allow movement around and positioning on the seabed 100.

Those skilled in the art will understand that the present invention can also be used to assemble a structure underwater. The opposite procedure will then be followed. The parts will be provided in a container on the seabed. The device 18 comprising the movable arm will be positioned in a first position near the seabed. Each time a part will be picked up from the container by the moving arm and the part will be attached to the parts already in place. In this way, a complete jacket can be erected. When the jacket 10 becomes so high that the movable arm 20 cannot reach the upper end, the support 22 of the movable arm is positioned again in a higher position.

Figures 9, 10 and 11 show another embodiment of the device 18 which comprises a movable arm 20. The device comprises a support 22 which comprises an insert device 150 which is designed to be inserted into a pipe end. The insert device is expandable to be firmly adapted to a touching end. In this respect, the insert device comprises expanding elements 152 which are movable from a retracted position to an outwardly directed position in order to grip the inner wall at the end of the tube. The expanding elements can also be retracted into a retracted position to detach the device 18 from the pipe end.

The device comprises a tower or swivel ring 63 which is rotatable around the support 22. The first segment 28a is attached to the swivel ring via hinge 27.

At a distal end of segment 28B, thrusters 154 are provided to move the arm.

A further actuator 33 is provided on a distal end 36 of the second segment. The actuator 33 is designed to move the processing tool relative to the second segment 28B.

In Figures 9 and 10, the processing tool shown is a cutting tool 51. The cutting tool comprises a port 156 which can be opened to admit a part of the structure and can then be closed to keep the part in an enclosed space. The gate 154 is connected to a body 159 of the cutting tool 51 via a hinge 158 and is operated by a driver. The cutting tool 51 comprises a ripping tool 160 which performs the cut.

The body 159 of the cutting tool is rotatable relative to the second segment via a rotary coupling 162. The hinge 84 provides two degrees of freedom. Together, the hinge 84 and the rotary link 162 provide three degrees of freedom for the cutting tool 51A relative to the second segment 28B. A quick coupler 164 is provided to quickly replace the cutting tool with another tool.

Figure 11 shows a gripping tool 50 having curved projections 166.

In figures 12A and 12B, the device 18 according to the invention can comprise a support which has clamps 23 which can be clamped on a part of a structure, which is shown with A1 in figure 12A. Alternatively, the device 18 may comprise an insert device 150 which, in use, is inserted into a cut-off bone 2 in a structure 10. This is shown by A2 in figure 12A. The insert device 150 is indicated by a broken line. In Figure 12B, it is shown with A3 that the device 18 which comprises an insert device 150 can also be inserted into one of the columns 168 which extend from the seabed upwards and in which the structure 10 is anchored.

In Figure 13, the device 18 in one embodiment further comprises a buoyancy device 170 which is connected to the arm 20 via a line 172. Buoyancy elements can also be attached directly to the arm, for example via a floating block 177. The buoyancy unit increases the lifting capacity of the movable arm. The position 174 where the buoyancy device is attached to the arm may be variable in direction 175, i.e., along the arm, by a driver 176.

In one embodiment, the buoyancy of the buoyancy device is variable in a controlled manner. In this regard, the buoyancy device comprises a control unit 178 to vary the buoyancy, for example by inflating the buoyancy device with a gas stored in a cylinder.

In one embodiment, as an alternative or in addition to the buoyancy device 170, a buoyancy device 180 is attached to a part 32 of the structure to be removed. The buoyancy device 180 is attached to the part directly or is alternatively attached via a line 172 to said part 32.

The work area 98 is a sphere around the support 22.

In Figures 14A and 14B, an auxiliary vessel 110 is provided in one embodiment. The vessel 110 comprises a crane 181 or other lifting device. A cable 180 extends from the crane to the device 18 which includes the movable arm 20. The cable is attached to the movable arm 20 near a joint 29. An anti-heave device 184 is provided on board the vessel to compensate for roll movements of the vessel . Anti-HIV devices 184 are known from the prior art.

In Figure 14B, the cable is attached to a part of the structure to be removed.

Figure 15 shows another embodiment of the device 18 according to the invention.

The device 18 comprises a central body 190 and two articulated arms 20A, 20B which are connected on a proximal end 34 to the central body 190. An arm 20A comprises a gripping tool 50 on a distal end 36 and an arm 20B comprises a cutting tool 51 on it distal end 36. The device 18 further comprises two supports 22A, 22B. The supports 22A, 22B are attached to the body via articulated legs 200A, 200B. The articulated legs are attached to the body 190 via hinges 202 and each comprises a first segment 205 and a second segment 206 attached to the first segment via a hinge 208. The articulated legs comprise actuators to move the legs. The supports 22A, 22B comprise clamps for gripping a part of the structure 10.

The arm 20A comprising the gripping tool 50 can provide assistance when the device 18 is to be moved to another position on the structure 10. The gripping tool 50 can grip the structure and provide additional stability. Then one of the legs 200A, 200B can release the structure 10 and be moved to another position on the structure and clamp the structure in this position. Then, the second leg 200 can release the structure and be moved to another position and then grasp the structure in this position. It is noted that the gripping tool 50 in this operation acts as a support 22.

It is also possible that a third leg 200 is provided to provide more stability and allow the device 18 to be attached to the structure in all three positions when a lifting operation is performed with the gripping tool 50, i.e., when a separated part 32 is lifted by the gripping tool 50. The third leg corresponds to the first and second legs 200A, 200B. It is also possible that arm 20B comprises a gripping tool 50 in addition to the cutting tool 51, so that the device 18 has two arms 20A, 20B and two legs 200A, 200B with which it can move, i.e. climb over the structure more or less as an orangutan.

Figure 16 shows another embodiment of the device 18. The body 190 can be divided into two body parts 190A, 190B. The medicine parts 190A, 190B comprise connectors 220A, 220B with which the parts 190A, 190B can be connected to and disconnected from each other.

In the disconnected mode of operation, there are two devices 18A, 18B which can each operate independently, for example to remove relatively light parts. In the linked mode, there is a single device 18. The device 18 can be more stable and perform operations that require more stability, such as the removal of heavy parts.

In Figure 17, two devices 18A, 18B are shown which both have a gripping tool 50 on a proximal end 34 and a gripping tool 50 on a distal end 36. The gripping tools 50 also act as a support 22. The devices 18A, 18B each also comprise a processing tool 51 on the proximal end and a processing tool 51 on the distal end. The processing tool can be a cutting tool 5 IA.

In Figure 18, a device 18 is provided which has a support 22 which is mounted to the structure 10 above the waterline 240. The tool 30 is designed to be provided below the waterline. A rail 242 may be provided along which the device 18 may be moved. The rail can extend horizontally. The rail 242 can also extend over a vertical distance, enabling the device 18 to move along said rail 242.

Figure 19 shows a device 18 comprising a digging tool 5 IB. The digging tool 5IB can be used to remove cuttings near a drilling platform. The cuttings typically form a pile around the structure 10. A container 40 as shown in Figure 2A can be provided where the cuttings 250 can be deposited with the digging tool 5IB. It is also possible to simply move the drill bit to thereby provide access to the bottom part 252 of the structure 10 which or would be impossible to reach. In a subsequent step, the bottom part 252 can be dismantled with the device 18 equipped with a cutting tool 51.

The support 22 can be of the insert type and be inserted into a column or a leg in the structure 10.

In Figure 20, a processing tool 51 in the form of a drill 51C is provided on the distal end of a movable arm. Another movable arm 20 is provided with a gripping tool 50.

In Figure 21, a processing tool 51 in the form of a sampling tool 5 ID is provided on the end of the arm 20. The sampling tool 5 ID is designed to take a sample from the structure 10, from the seabed 100, from the water, from the cuttings 250 or another sample. The digging tool 5 IB, the drill 51C and the sampling tool 5 ID are attached to the arm 20 via a quick coupling, to enable quick exchange of the processing tool 51 with another processing tool 51.

It is obvious to those skilled in the art that the details and layout of the part can be varied a great deal without departing from the idea of the invention and the scope of the claims.

Claims (45)

1. Method for performing an underwater operation on a structure (10) or in the vicinity of the structure, where the method comprises: providing a device (18) comprising a movable arm (20), where the device is designed to perform an underwater operation on the structure or in the vicinity of a structure, wherein the device comprises:<*>at least a first support (22) which is designed to be connected to the structure, where the support is configured to transmit significant forces in three dimensions and significant moments about the X-axis, Y-axis and Z-axis from the movable arm of the structure, including a vertical force necessary for the device's lifting operations,<*>at least a first articulated movable arm (20) directly or indirectly attached to a proximal end (34) of said support, wherein the first movable arm comprises a first tool (30) attached to a distal end (36) of said first movable arm, wherein the first tool (30 ) is movable in a three-dimensional working area (98) around the at least first support,<*>at least one actuator (33) configured to controllably move the first tool (30) in the three-dimensional working area to position re the first tool at a target location,<*>a control device (56) configured to control the at least one the actuator and the tool during operation, attach the device to the structure via the at least one support, move the tool in three dimensions and perform an operation under water, where forces and moments that arise during the operation are transferred to the structure. 2. Method according to claim 1, which comprises assembling or disassembling a structure (10) which is located at least partially under water, where the method comprises: providing a device comprising at least one movable arm (20), where:<* >the at least one movable arm comprises at least a first segment (2 8A) and a second segment (28B) connected to each other via a first hinge (29),<*>the support (22) is attached to a proximal end (34) of the first segment via the at least one support hinge (27, 61), wherein the support is designed to be mounted to the structure,<*>the tool (30) is mounted on a distal end (36) of the second segment,<*>the at least one actuator (33) is configured to: o controllably move the first segment relative to the support, and o controllably move the second segment relative to the first segment, to position the processing tool at a target location in a working area of the arm, the<*>control device (56) is configured to control the at least one actuator and the processing tool during operation, perform a processing operation on the structure to assemble or dismantle the structure. 3. Method according to claim 1 or 2, wherein the tool comprises a processing tool selected from a group comprising: a cutting tool (5IA) for cutting into the structure, a digging device (5 IB) for digging on the seabed to collect material located on the seabed, a drilling device (51C) for drilling a hole in the structure, and/or a welding device for performing a welding operation, a sampling device (5ID) for taking a sample, especially from the structure, from the seabed or from the water. 4. Method according to claim 3, where the processing operation comprises: gripping a part (32) of the structure with the gripping tool, cutting the structure with the cutting tool (51) so that said part is separated from the structure. 5. Method according to any one of claims 3 or 4, comprising simultaneously gripping the part with the gripping tool (50) and cutting the structure with the cutting tool (51), thereby preventing the part from falling when the part is separated from the structure. 6. A method according to any one of claims 1-5, wherein the cutting tool is movable relative to the gripping tool, and allows a part of the structure to be held by the gripping tool while the cutting tool cuts the structure at various positions necessary to separate the part from the structure, the method comprising: grab a part of the structure to be separated from the structure with the gripping tool, move the cutting tool to other locations and cut into the structure at those various locations to separate the part from the structure while maintaining grip on the part with the grip tool. 7. Method according to any one of claims 1-6, which comprises: providing a container (40) on the seabed with a working area for it movable arm, each time separating a part from the structure, placing the separated parts in the container with at least one arm, lifting the filled container to the water surface (111), transporting the container to a remote location with a vessel (120, 130). 8. Method according to any one of claims 1-7, wherein the support comprises at least one clamp (24A, 24B), wherein the method comprises: clamping the support (22) to the structure in a first position, removing at least one first part from the structure, and in particular as many parts as is within the working range of the movable arm in the first position, release the at least one clamp, move the support (22) to a second position on the structure and clamp the structure at the second position, removing at least one second part from the structure, and in particular as many parts as is within the working range of the movable arm in the second position, repeat these steps until the structure is, so to speak, dismantled. 9. Method according to claim 8, which comprises clamping the at least one clamp on a vertical beam (2) or substantially vertical beam (2) on the structure and moving downwards along said beam from said first position to said second position and further downwards until the structure is essentially dismantled. 10. Method according to any one of claims 1-9, wherein the control device comprises: a data processing device comprising a memory configured to store:<*>geometric data relating to the original shape of the structure,<*>disassembly data relating to the progress of disassembly of the structure and the relevant shape of the structure, one or more sensors which are designed to determine a current position of the arm and of the processing tool relative to the structure, and where the method includes: - loading the geometric data into the memory, - determining a part that should removed from the structure and determine a target position for the processing tool on the basis of the geometric data and the disassembly data, - move the processing tool to the target position, - remove a part of the structure by grasping the part, cutting into the structure until the part is separated and removing the part away from the structure, - update the disassembly data with data applicable to the removed part, repeat steps i until the structure is dismantled. 11. Method according to any one of claims 1-10, which comprises: cutting the structure at a cutting level, where a top part of the structure is separated from a bottom part of the structure, lifting the top part of the structure with a lifting device on a vessel, removing the top part from the site, dismantling the bottom part of the structure according to the method according to claim 1. 12. Method according to claim 11, where the top part is removed from the vessel. 13. Method according to claim 11 or 12, where the top part is removed on a transport barge. 14. Method according to any one of claims 11-13, where the top part hangs from the lifting device in the removal step. 15. Method according to any one of claims 11-14, where the dismantled sections from the bottom part are collected in at least one container on the seabed. 16. Method according to claim 15, where the filled containers are removed from the seabed with a lifting device on a vessel. 17. Method according to any one of claims 1-15, comprising: providing a first of said movable arms, providing a second of said movable arms, gripping a part of the structure with the gripping tool on the first movable arm, cut into the structure with the cutting tool on the other movable arm like this that said part becomes separated from the structure, move the separated part away from the structure with the first movable the arm. 18. Method according to claim 16, comprising: gripping the first movable arm with the gripping tool on the second movable arm, release the support of the first movable arm from the structure, move the first movable arm with the second movable arm so that the support for the first movable arm is moved from a first support position to a second support position, thereby changing the working area of the first movable arm. 19. Method according to any one of claims 1-18, comprising: providing a device comprising a movable arm, wherein the device further comprises:<*>a body (190), where the first articulated movable arm (20A) is connected to the at least one support via said body, Where the first movable arm comprises a gripping tool (50),<*>a second articulated movable arm (20B) directly or indirectly connected to a proximal end (34) of said support, wherein the second movable arm comprises a processing tool (51) attached to a distal end of said second movable arm, wherein the processing tool is movable in a three-dimensional work area around at least the first support, perform a processing operation on the structure with the grip tool and the processing tool. 20. Method according to any one of claims 1-19, which comprises: providing a device, where both on the proximal end (34) and the distal end (36) of the articulated movable arm is provided with:<*>a support (22A, 22B) and<*>a processing tool (30A, 30B), wherein the proximal end and the distal end are configured to exchange functions, - in a first mode of operation, mounting the support (22A) on the proximal end of the structure and performing a processing operation with the processing tool (30A) on the distal end, and - in a second mode of operation, mounting the support (22B) on the distal end of the structure and perform a processing operation with the processing tool (30B) on the proximal end. 21. Method according to any one of claims 1-20, which comprises providing a vessel (110) above the structure and assisting the operation by attaching a line (180) from the vessel to the articulated, movable arm or to a part of the structure, and exercising an upward force on the articulated, movable arm or on the part of the structure via the line. 22. Method according to any one of claims 1-21, comprising providing at least one buoyancy device (170) and assisting the operation by attaching the buoyancy device to the articulated, movable arm or to part of the structure, directly or via a line, and exerting a upward force on the articulated movable arm or on the part of the structure via the buoyancy device. 23. A method according to any one of claims 1-22, comprising connecting a digging device (5 IB) to the distal end of at least one articulated, movable arm and performing at least one digging operation in the vicinity of the structure. 24. Method for assembling or disassembling a structure (10) which is located at least partially underwater, where the method comprises: providing a device comprising at least one movable arm (20), where the device comprises:<*>at least one movable arm comprising at least a first segment (28A) and a second segment (28B) which are attached to each other via at least a first hinge (29),<*>a support (22) connected to a proximal end (34) of the first segment via at least one support hinge (27, 61), wherein the support is designed to be mounted on the structure or placed on the seabed,<*>a processing tool (30) mounted on a distal end (36) of the second segment, <*>at least one actuator (33) that is configured to: o controllably move the first segment relative to the support, and o controllably move the second segment relative to the first segment to position the processing tool at a target location in a working area of the arm,<* >a control device g (56) which is configured to control the at least one actuator and the processing tool during operation, perform a processing operation on the structure to assemble or disassemble the structure. 25. Device (18) comprising a movable arm (20), wherein the device is designed to perform an underwater operation on an at least partially submerged structure or in the vicinity of the at least partially submerged structure, wherein the device comprises: at least a first support (22) designed to be attached to the structure, where the support is configured to transmit significant forces in three dimensions and significant moments about the X-axis, Y-axis and Z-axis from the movable arm to the structure, including a vertical force necessary to hip the operations of the device, at least a first joint, movable arm (20) directly or indirectly attached to a proximal end (34) of said support, wherein the first movable arm comprises a first tool (30) attached to a distal end (36) of said first movable arm, wherein the first tool is movable in a three-dimensional working area around it at least the first support, at least one actuator (33) configured to controllably move it first tool in the three-dimensional workspace to position the tool at a target location, a control device (56) configured to control the at least one the actuator and the tool during operation. 26. Device comprising a movable arm (20) according to claim 25, wherein the device is configured to disassemble or assemble a structure that extends at least partially underwater, where: the movable arm comprises at least a first segment (2 8A) and a second segments (28B) which are attached to each other via at least a first hinge (29), the support (22) is attached to a proximal end (34) of the first segment via at least one support hinge (27, 61), wherein the support is designed to be mounted on the structure, the tool (30) is on a distal end (36) of the second segment, the at least one actuator (33) is configured to:< *>controllably moving the first segment relative to the support, and<*>controllably moving the second segment relative to the first segment to position the tool at a target location in a working area of the arm, the control means (56) being configured to control the at least one the actuator and the tool during operation. 27. Device comprising a movable arm according to claim 25 or 26, wherein the tool (30) wherein the tool comprises: a gripping tool (50) for gripping a part of the structure, and/or a processing tool (51) for performing a processing operation on the structure or near the structure. 28. Device comprising a movable arm according to claim 27, where the processing tool (51) is selected from the group comprising: a cutting tool (5 IA) for cutting into the structure, a digging tool (5IB) for digging in the seabed or for collecting material which lying on the seabed, a drilling tool (51C) for drilling a hole in the structure, a sampling tool (5 ID) for taking a sample, especially from the structure, from the seabed or from the water. 29. Device comprising a movable arm according to any one of claims 25-28, comprising a gripping tool and a cutting tool, wherein the cutting tool is movable relative to the gripping tool, which allows part of the structure to be held by the gripping tool while the cutting tool cuts the structure at various positions as are necessary to separate the part from the structure. 30. Device comprising a movable arm according to any one of claims 25-29, where a distal end (36) of the movable arm has three degrees of freedom relative to the support (22) of the movable arm so that the distal end (36) can be positioned within the working range of the movable arm, and wherein the tool (30) is rotatable about three independent axes of rotation about the distal end, thereby allowing the tool to be oriented in any direction in said position. 31. Device comprising a movable arm according to any one of claims 25-30, comprising a gripping tool and a cutting tool, wherein the cutting tool is connected to the gripping tool or to the movable arm via a movable cutting arm which provides the cutting tool with a working area extending around the gripping tool . 32. Device comprising a movable arm according to any one of claims 25-31, wherein the support comprises a clamping device comprising clamping elements designed to be clamped on a vertical or so to speak vertical beam on the structure. 33. Device comprising a movable arm according to any one of claims 25-32, comprising: a first clamp (24A), a second clamp (24B) spaced from the first clamp, and at least one support beam (26A, 26B) connecting the first and second clamps with each other, where the first segment is connected to said support beam via at least one support hinge (27, 61). 34. Device comprising a movable arm according to any one of claims 25-33, wherein the control device comprises: a data processing device comprising a memory configured for to create: • geometric data relating to the shape of the structure, • assembly data or disassembly data relating to the individual steps of assembling or disassembling the structure, one or more sensors (102, 103, 104) designed to determine a current position of the arm and the processing tool relative to the structure. 35. Device comprising a movable arm according to any one of claims 25-31, which further comprises: a body (190), in which the first articulated movable arm is connected to the at least one support via said body, wherein a gripping tool is provided at the distal end thereof, a second articulated movable arm (20B) directly or indirectly connected to a proximal end (34) of said support, where the second movable arm comprises a processing tool (51) connected to a distal end of said second movable arm, where the processing tool is movable in a three-dimensional working area around at least the first support. 36. Device comprising a movable arm according to claim 35, which further comprises: a first support attached to the body and which on a distal end thereof comprises a clamp to be clamped to the structure or an insert designed to be inserted into the structure to provide a secure coupling with the structure, and a second support attached to the body and comprising at a distal end thereof a clamp to be clamped to the structure or an insert designed to be inserted into the structure to provide a secure connection with the structure. 37. Device comprising a movable arm according to claim 34 or 35, wherein the first support comprises a first articulated leg which is attached on a proximal end to the body and which on a distal end thereof comprises the clamp or insert device, and where the second support comprises a second articulated leg which is attached on a proximal end to the body and which on a distal end thereof comprises the clamp or insert device, wherein the first and second legs comprise actuators for moving the first and second clamps in a three-dimensional working area around the body. 38. A device comprising a movable arm according to any one of claims 25-37, wherein both on the proximal end (34) and on the distal end (36) of the articulated arm there is provided: a support (22A, 22B), and a processing tool (5 IA, 5 IB), where the proximal end and the distal end are configured to switch functions, where: - the support (22A) on the proximal end in a first operating mode is connected to the structure and the processing tool (5IA) on the distal end is operable to perform a processing operation, and - the support (22B) on the distal end in a second operation mode is connected to the structure and the processing tool (5IB) on the proximal end is operable to perform a processing operation. 39. Device comprising a movable arm according to any one of claims 25-37, wherein the at least one articulated arm comprises a first, a second and a third segment (28A, 28B, 28C) connected to each other via a first and a second hinge ( 29A, 29B). 40. Device comprising a movable arm according to any one of claims 25-39, further comprising at least one buoyancy device attached to the at least one articulated arm to increase the lifting capacity of the movable arm. 41. Combination of a first device (18A) comprising a movable arm according to any of claims 25-40 and a second device (18B) comprising a movable arm according to any of claims 25-40. 42. Combination according to claim 41, wherein the first device (18A) comprises a first coupling part (220A) and the second device (18B) comprises a second coupling part (220B), where the first and second coupling parts are configured to be connected to each other to form a unified movable arm arrangement comprising at least two movable arms. 43. Combination according to claim 34, wherein the coupling parts are substantially provided in a central area of the first movable arm and the second movable arm. 44. Combination for dismantling a structure that at least partially extends underwater, where the set-up comprises: at least one device comprising a movable arm according to claim 25, and at least one container for receiving removed parts from the structure. 45. Movable arm (20) for disassembling or assembling a structure that at least partially extends underwater, wherein the movable arm comprises: at least a first segment (28A) and a second segment (28B) which are connected with each other via at least a first hinge (29), a support (22) attached to a proximal end (34) of the first segment via at least one support hinge (27, 61), wherein the support is designed to be mounted on the structure or to be placed on the seabed (100), a processing tool (30) mounted on a distal end (36) of the other the segment, at least one actuator (33) configured to:<*>controllably move the first segment relative to the support, and<*>controllably move the second segment relative to the first segment to position the processing tool at a target location in a working area of the arm , a control device (56) configured to control the at least one the actuator and processing tool during operation.