Patent Application
20130336724
The present invention relates to the field of disassembling structures in a marine environment. The present invention further related to performing other operations on structures in a marine environment.
In the past years, many structures have been built at sea, in particular for exploration and production of hydrocarbons. These structures are generally partially submerged. Often, these structures rest on a seabed and protrude above the water level. Structures at sea have been built for other purposes as well.
At the end of the economic lifespan, such a structure often needs to be removed or disassembled. This is often a difficult and costly process. Often, divers are used to perform under water operations. This brings along great risks to human life. Moreover, the use of divers at sea is costly and time consuming. Sometimes, ROV's are used. However, ROV's also have certain limitations. ROV's can only exert limited forces. ROV's further are sensitive to currents, just as divers. Sometimes a special-purpose vessel is used to remove such structures. These vessels are very expensive.
The present invention relates in particular to jacket structures. A jacket comprises many tubulars which are interconnected and form a lattice structure. The beams are generally made from steel. A jacket generally comprises a number of beams which are substantially upstanding and which extend from a base of the jacket to a top of the jacket.
The upstanding beams are generally connected to one another via horizontal and diagonal cross-beams.
Once a jacket reaches the end of its economic or technical lifespan, it may need to be removed. The required removal is dependent on local administrative requirements and can be in part or in full.
In a known method of removing a jacket, a heavy lift vessel is used to support a top part of the jacket. Subsequently, the jacket is cut at a certain distance above the seabed. The section above the cut is lifted and removed with the heavy lift vessel, and the section below the cut remains on location. A further cutting and lifting operation may be required to remove a next part.
The cutting of the jacket generally is a time consuming and expensive operation. Generally, a large vessel with a crew is required in order to perform the cutting. Divers or one or more ROV' s and special cutting and lifting equipment are required for the actual cutting itself. For the lifting operation, heavy lift capability is required, which is expensive.
The known removal operation has a further disadvantage in that bad weather can cause significant delays, which further increase the costs. There is a need in the field of the art for more efficient and cost-effective way of removing jacket structures.
Further, construction or repair of structures at sea is also rather costly. Also during construction, under water operations are necessary. Divers and ROV's are often used, but have the same disadvantages as during the removal or disassembling of a structure. Some apparatuses for underwater work other than ROV's have been conceived, but none of these apparatuses provide the capabilities needed. There is also a need in the art for improved methods of constructing or repairing structures at sea.
It is an object of the invention to improve operations on structures which are at least partially submerged.
A device is provided for performing an under water operation on an at least partially submerged structure or in the vicinity of the at least partially submerged structure, the device comprising:
With the present invention, a large jacket structure can be disassembled. It is possible to disassemble a jacket structure having a height of for instance 100 meter or more. The disassembling operation can be performed substantially independently by the movable arm. The couplings allow coupling and uncoupling of the device to and from the structure in a simple manner. The at least one rail may have a length of more than 10 meter, i.e. 10-150 meters, depending on the size of the structure.
In an embodiment, the base comprises a buoyancy element. The buoyancy element allows easier transportation and handling as well as accurate positioning of the device relative to the structure. The buoyancy element may have a length of more than 10 meter, i.e. 10-150 meters, depending on the size of the structure.
In an embodiment, the buoyancy element is elongate and wherein the couplings are connected to the buoyancy element at different positions along the length of the buoyancy tank. In a further embodiment, the buoyancy element is elongate and constructed to be mounted to a leg of the structure in an orientation which is substantially parallel to said leg.
In an embodiment, the base comprises a first rail and a second rail which extend parallel to one another at a distance from one another, wherein the support carriage is constructed to engage both the first and the second rail. In an embodiment, the at least one rail is mounted to the buoyancy element. When the buoyancy element forms a structural component to which the couplings and the rails are mounted a sturdy structure is obtained which can be coupled to a leg of a structure relatively easy.
In an embodiment, the buoyancy element has a longitudinal axis, wherein the at least one rail extends parallel to the longitudinal axis of the buoyancy element.
In an embodiment, the device comprises a plurality of couplings which are mounted to one side of the buoyancy element, wherein the at least one rail is mounted to a different side of the buoyancy element. This configuration allows a substantial freedom of movement for the movable arms.
In an embodiment, the device comprises at least two movable arms, each comprising a support carriage and each being movably connected to the at least one rail. This configuration allows cooperation between two movable arms. The movable arms may be connected to the same rails. The two movable arms are movable over the rails independently from one another.
In an embodiment, the device comprises two sets of rails, and wherein at least one movable arm is movably connected to each set of rails. The sets may be located on different sides, in particular opposing sides of the buoyancy element.
In an embodiment, the movable arm comprises a connection member constructed to be connected to a lifting cable which extends between a surface vessel and the movable arm.
In an embodiment, the movable arm comprises at least two segments connected to one another by a hinge and wherein the connection member is provided near said hinge.
The present invention further relates to an assembly comprising:
The present invention further relates to a method of performing an under water operation on an at least partially submerged structure or in the vicinity of the at least partially submerged structure, the method comprising:
In an embodiment of the method, the device comprises a buoyancy element, and wherein the method comprises:
In an embodiment of the method, the buoyancy element is elongate and is connected substantially parallel to a leg of the structure.
In an embodiment of the method, the device comprises at least one rail, wherein the movable arm comprises a support carriage which engages with the rail and is constructed to move along said rail, wherein the movable arm travels along said rail from one position to another position, and performs operations at said positions.
In an embodiment of the method, the device comprises two or more movable arms which are movably connected to the at least one rail and which simultaneously perform operations on the structure, in particular in cooperation.
In an embodiment, the method comprises removing several parts of the structure by the movable arm, and leaving a leg to which the device is connected and supporting beams which directly support the leg intact.
In an embodiment, the method comprises positioning a vessel in the vicinity of to the device and providing one or more connection lines between the device and the vessel for conveying:
In an embodiment, the method comprises:
The previous and other features and advantages of the present invention will be more fully understood from the following detailed description of exemplary embodiments with reference to the attached drawings.
With reference to
The device 10 is being towed in a substantially upright orientation and is submerged for the greater part, with a small part protruding above the water line 5. The device 10 may also be towed in a different orientation, for instance substantially horizontal.
The buoyancy element 16 internally comprises multiple compartments which are located along the length of the buoyancy element. The compartments are separated from one another by bulkheads, as is commonly known in the prior art. The buoyancy element comprises openings 18 with controllable valves. The valves allow ballasting of the buoyancy element in a controlled manner in order to submerge the device. At least one pump is provided for blowing compressed air, nitrogen or another gas into the compartments for removing the water when required, thereby raising the device 10. When multiple valves are used, in a preferred embodiment, these valves can be operated from a single connection point. It is also possible that the device 10 comprises several separate buoyancy elements.
Clamps 20 are connected to the buoyancy element 16. The clamps are positioned at a distance from one another. Two clamps 20 may be provided, but more clamps may also be provided. The clamps are configured to be connected to a leg of a structure. To this end, the clamps 20 are hydraulically operated. The clamps 20 may also be pneumatically or electrically operated. The clamps 20 are constructed to transfer substantial forces in three dimensions and substantial moments about the X-axis, Y-axis and Z-axis from the device 10 to the structure 40.
In particular when the device 10 performs a lifting operation, a downward vertical force is exerted by the device 10 via the couplings 20 onto the structure 40. If a current exists in the water, horizontal forces will also be transferred via the clamps 20 to the structure 40.
The device 10 comprises two rails 22A, 22B which are rigidly connected to the buoyancy element 16. The rails 22A, 22B extend parallel to a main axis 24 of the buoyancy element 16. The rails 22A, 22B may be connected directly to the buoyancy element or may be connected to the buoyancy element via struts.
Two articulated movable arms 30 are connected to the rails 22A, 22B. Each movable arm 30 comprises a carriage 32 constructed to move along the rails 22A, 22B. The carriage comprises rollers or skids 36 which engage the rail and fixate the carriage in two directions transverse to the rail (Y-direction and Z-direction) while allowing a movement parallel to the rail X-direction).
Each movable arm further comprises a turret 34 which is rotatably mounted to the carriage 32 and projects from the carriage. The turret 34 comprises an internal drive which rotates the turret relative to the carriage. The movable arm will discussed further herein below.
The two movable arms 30 are movable over the rails independently from one another. The two movable arms 30 including the carriages 32 are also independently movable from one another relative to the base 15.
Turning to
When the auxiliary vessel 50 arrives at the structure 40, the buoyancy element 16 is ballasted so that it submerges. Optionally the element is ballasted such that it rotates. During the connection operation, the device 10 may remain connected to the vessel via one or more lines for more control of the movement. The clamps 20 engage a leg 42 of the structure 40 and are hydraulically energized to firmly clamp the leg 42. The device is 10 now rigidly coupled relative to the structure 40. The device may be completely submerged or may be partially above the water line 5.
In
The arms 30 have a three-dimensional operating range relative to the support carriage 32. Further, due to the ability to travel along the rail 22, the arms 30 have an operating range which is large enough to cover a substantial portion of the structure 40. In this way, the arms 40 can disassemble the structure 40 or at least disassemble a substantial part of the structure 40.
It is possible that the working range of the arms 30 is too small to cover the entire height of the structure 40 or to cover the entire horizontal span of the structure 40. In that case, the device 10 may need to be repositioned from time to time to change the working range and allow the tools of the arms to reach other portions of the structure. The repositioning may involve connecting the device 10 to another leg 42.
During operation, the device 10 is connected to the auxiliary vessel 50 via lines 75. These lines 75 may comprise a power cable for providing electrical power, a hydraulic cable for providing hydraulic power, control lines for controlling the various actuators, pumps and valves. Also lines for relaying signals from sensors may be provided. During operation, the auxiliary vessel stays in the vicinity of the device 10. In case of storm, the connection lines 75 may be disconnected and the auxiliary vesse 150 may be moved to a safer area. The lines may be attached to one another to form an umbilical.
Turning to
A rack 70 is connected to the buoyancy element 16 between the rails 22A, 22B and extends parallel to the rails 22A, 22B. The support carriage 32 comprises a pinion 72 which is connected to a drive 74. The rack and pinion allows the movable arm to travel in a controlled manner along the rails 22A, 22B. Other ways of controllably moving the support carriage 32 of the movable arm relative to the buoyancy unit are conceivable. For instance, in another embodiment, the carriage comprises rollers instead of skidding elements. One or more of the rollers may be driven by a drive 74.
The rails 22A, 22B are connected to a different side of the buoyancy element 16 than the clamps 20.
The movable arm 30 is connected at a proximal end 31 to the turret 34 via a first hinge 35. The movable arm comprises a first segment 37 and a second segment 38, which are interconnected via a second hinge 39. A tool 60 is connected to the second segment 38 via a third hinge 62 at a distal end 29 of the arm 30. The tool 60 itself is rotatable relative to a socket 63 via which the tool 60 is connected to the hinge 62. The arm 30 is equipped with actuators to allow controlled movement of the arm, which are discussed in more detail below.
The tool 60 is a cutting tool, and can be a hydraulic cutter, a saw, a flame cutting tool, a welding tool, or a laser device. The tool may also be a gripping tool, drilling tool or a different tool. The tool has a three dimensional working range about the carriage 32. The tool 60 is rotatable about three independent axes of rotation relative to the distal end 29, resulting in six degrees of freedom relative to the carriage 32.
A control unit is provided on board the auxiliary vessel to control the device 10. One or more operators may be present to control the device, or the device 10 may be fully automated.
In an embodiment, the device 10 comprising the movable arm 30 comprises several sensors which are used for determining a position of the movable arm and of the processing tool relative to the structure. These sensors may be ultrasonic sensors, video cameras and/or touch sensors which register an engagement of the movable arm with the structure. Other sensors may also be provided, such as a current sensor for measuring the current or a weight sensor for measuring the weight of a part of the structure 40 which is lifted by the arm 30.
The clamps 20 comprise two clamp halves 21A, 21B which are hydraulically operated to move away from one another or to move toward one another, i.e. to move between an open position and a closed position. The clamps are mounted to the buoyancy element 16 via struts 26.
Turning to
Further the two movable arms can pass one another when travelling along the length of the base 15, because they are connected to different rails.
Turning to
Prior to operation, the device 10 is transported to the structure 40 by an auxiliary vessel 50. The device 10 is lowered via lines or cables by a crane or another hoisting device on the vessel 50. The device 10 is positioned parallel to and in engagement with a leg 42 of the structure 40. The clamps 20 are hydraulically operated to firmly grip the leg 42.
Turning to
Another hinge 39 connects the second segment 38 to the first segment 37. Another actuator 77 is provided to rotate the second segment 38 segment relative to the first segment. The actuator 77 extends between a pivot 79 on the first segment and a mechanism 81 which comprises multiple axes and beams and which acts as a lever.
The tool 60 in
A connection member 82 is provided on the first segment near the first hinge 39, the purpose of which is discussed in connection with
The support carriage 32 comprises two sliding or rolling elements 36 which are engaged with the first rail 22A at a distance 47 from on another, and at least two sliding or rolling elements 36 engaged with the second rail 22B at a distance 47 from one another.
Turning to
Turning to
The lifting cable 84 may be connected to a hoisting device 85 on the vessel 50. The hoisting device comprises a winch 87 and a boom 86 which extends outboard of the vessel. In operation, the lifting cable 84 can provide an additional lifting force F, substantially increasing the lifting capacity of the arm 30. The lifting cable 84 can also be used in the embodiments of
In another embodiment, the connection member 82 is provided on the second segment 38, in particular near the third hinge 62.
It will be obvious to a person skilled in the art that the details and the arrangement of the parts may be varied over considerable range without departing from the scope of the invention as defined by the claims. In particular, the device according to the invention may be used for different operations than a disassembling operation. Maintenance work, cleaning operations, and other operations may also be performed.
Further, the skilled person will understand that the present invention may also be used for assembling a structure under water.
The following embodiments or aspects of the invention may be combined in any fashion and combination and be within the scope of the present invention, as follows:
wherein the base comprises at least one rail (22A, 22B), wherein the movable arm (30) comprises a support carriage (32) which engages with the rail in order to allow the movable arm to move along said rail.
wherein the device is connected to the structure (40), wherein the vessel is connected to the connection member (82) via a lifting cable (84), wherein the vessel exerts an upward force on the movable arm via the lifting cable.
Embodiment 14. Method of performing an under water operation on an at least partially submerged structure (40) or in the vicinity of the at least partially submerged structure, the method comprising:
from the vessel to the device or vice versa.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009005 | Jun 2012 | NL | national |
This application claims the benefit of Netherlands Application No. 2009005, filed Jun. 14, 2012, and of U.S. Provisional Application No. 61/659,625, filed Jun. 14, 2012, the contents of all of which are incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 61659625 | Jun 2012 | US |
