The present invention relates to a device for the removal of a permanent structure at sea. More particularly, it relates to a device for the removal of a permanent structure at sea, wherein there is temporarily a need for at least a landing place for helicopters, living quarters and a crane. The invention also relates to a method of using the device.

In connection with the dismantling of a permanent installation at sea, it will be necessary to remove the local infrastructure on the permanent installation. This may be, for example, living quarters, lifting equipment and a landing place for helicopters. It will further be necessary to disconnect electrical power, pressurized air and drainage water, for example. This leads to the permanent structure, which may be, for example, a platform that has been used in connection with the recovery of petroleum, being inhabitable during the dismantling period.

A known way of solving this has been to use a floating hotel, a so-called floatel, and place it close to the permanent structure so that a footbridge may be established between the two units. This solution has turned out to have several drawbacks. Much preparatory work is required before the floatel may be put to use. The floatel may have to be booked a long time in advance and, thus, the solution is not very flexible. Further, such a floatel is very vulnerable to the weather. In harsh weather, it may be necessary to remove the floatel from the permanent structure and it will not be possible to move between the units. In sum, the effect of this is that using a floatel in connection with removing permanent structures at sea may be a time-consuming, not very flexible and expensive solution.

The patent document NO 325577 discloses a jack-up platform and a method of removing an offshore platform. The jack-up platform is provided with break-up implements that are positioned close to the offshore platform. As the deck structure of the offshore platform is removed, the break-up implements are moved in over the offshore platform by means of a movable deck on the jack-up platform. This solution has turned out to be very expensive and demanding, and the jack-up platform has never been realized.

From the patent document US 20100143044 Al, a device and a method for providing a module-based platform for oil and gas exploration and recovery on land or in very shallow waters are known. It is the platform itself that is made up of modules, whereas necessary equipment for carrying out the work is placed on the modular units afterwards.

In the patent document US 4666340, a device and a method for positioning equipment modules on an offshore platform are disclosed. The modules may be replaceably fixed to the platform and are arranged to contain necessary equipment adapted for different phases of the work on an offshore platform. For example, modules containing drilling equipment may be replaced with modules containing production equipment in a later phase of the work on the platform. The main object of this invention is to save space by equipment which is not relevant for a current work phase not being kept on the platform. The modules as such are not self-sufficient and will be dependent on being connected to local infrastructure on the platform. Further, each of these modules must be tailored to the geometries of the individual platforms and the specifications of the reservoir.

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

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

In a first aspect, the invention relates to a device for the removal of a permanent structure at sea, the device being arranged to be placed on the permanent structure, the device including a base complementarily fitting a supporting structure on the permanent structure, and the device further including :

- living quarters;

- a landing place for helicopters; and

- a crane, characterized by the device further including at least one of

- an electric generator, a compressor and a fuel tank.

The device according to the invention is substantially independent of the permanent structure which is to be removed. It is sufficient that the permanent structure has sufficient space and structural integrity to receive the device. In one embodiment, a fuel tank may, for safety reasons, be placed at a distance from the device itself.

An advantage of a device in accordance with the invention is that it is arranged to be put to use immediately after it has been placed on the permanent structure at sea, as it is at least partially self-sufficient in energy. This could save an operator much time and money, as the work on the permanent structure may be started immediately, at least for a smaller group of people.

The device may further include a water tank. The water tank may be an integral part of the device, or the water tank may be a portable one and be fitted to the device after this has been placed on the permanent structure. The device may then also be self-sufficient in water, at least partially.

The device may also include equipment for treating waste water. The equipment for treating waste water may be integrated in the device or it may be connected to the device externally to the device.

The device may further include a breathing-air plant. Depending on the type of work to be carried out, it may be advantageous and/or necessary to use breathing air while working.

In one embodiment, the device may include an air-drying plant. This could be particularly appropriate when a compressor is used.

Further, the device may include at least one of a storage facility, a workshop, a living room, a kitchen and a locker room.

In sum, the device may be a toolbox with equipment that may be necessary during the removal of a permanent structure at sea. The device may be provided with different equipment for removing different permanent structures. Further, the device may be delivered with full fuel and water tanks and empty drainage tanks so that the device may be put to use immediately. The device may also, if the integrity of the permanent structure allows it, be connected to the infrastructure of the permanent structure, so that access to larger water, fuel and sewage tanks is provided and thereby the filling/emptying intervals may be reduced.

In a second aspect, the invention relates to the use of a device in accordance with the above description in connection with the removal of a permanent structure at sea.

In a third aspect, the invention relates to a method of using a device for the removal of a permanent structure at sea, the method including the steps of:

- providing the device with a base that complementarily fits a supporting structure on the permanent structure; and

- providing the device with living quarters, a landing place for helicopters and a crane; characterized by the method further including the step of:

- providing the device with at least one of an electric generator, a compressor and a fuel tank.

The method may further include the steps of:

- placing the device on the permanent structure;

- removing the permanent structure, at least partially; and

- removing the device from the permanent structure.

Further, between the steps of placing and removing the device from the permanent structure, the method may further include the step of moving the device from a first position to a second position on the permanent structure. This may be appropriate to be able to remove various portions of the permanent structure.

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

Figure 1 shows a device according to the invention in a perspective view;

Figure 2 shows, in a perspective view and on a smaller scale, the device just before it is landed on a permanent structure; and

Figure 3 shows the device after it has been placed on the permanent structure.

In what follows, the reference numeral 1 indicates a device in accordance with the invention. The device 1 includes a base 2 which complementarily fits a supporting frame 26 on a permanent structure 24 located at sea, see figure 2. The base 2 may be provided in different sizes to be adapted to supporting frames of other permanent structures, not shown, at sea. The adaptation of the base 2 to other permanent structures may include changes in terms of size and strength of a character requiring expert knowledge.

The device includes, among other things, living quarters 4, a landing platform 6 for helicopters and a crane 8. Further, the device 1 is provided with a section 10 accommodating electric generators 12, compressors 14, a workshop 16 and storage containers 18, among other things. Thus, the device 1 is, at least partially, self-sufficient in energy, tools and storage space, and could thereby be put to use immediately after the device 1 has been placed on the supporting frame 26 of the permanent structure 24.

The device 1 is further provided with a connection point 20 for a lifting device 22, see figure 2. It will be understood that a device 1 in accordance with the embodiment shown may weigh in the order of 1000-2000 tonnes, and that the lifting device 22 must be correspondingly powerful. The lifting device 22 is connected to a lifting vessel not shown.

In figure 3, the device 1 is placed on the supporting frame 26, and the device 1 may then immediately be put to use. This also applies to the living quarters 4 with associated fresh water from fresh-water containers 28 and drainage for treated waste water, Fuel tanks 30 are placed at a distance from the device 1 and are arranged to be connected to the electric generators 12, among other things, as soon as the device 1 has been placed on the structure 24.