JP7464658B2 - Offshore work equipment and manufacturing method thereof - Google Patents

Description

The present invention relates to offshore work equipment that can be used for constructing offshore facilities such as offshore wind power generation facilities, and a method for manufacturing the same.

Offshore wind power generation is attracting attention from the perspective of effective use of natural energy.

Offshore work equipment such as a self-elevating platform (SEP) is often used to construct offshore wind power generation facilities. A self-elevating platform usually has multiple piers and a deck supported on these piers so that it can be raised and lowered freely (Patent Document 1, Patent Document 2). A work crane is mounted on the deck, and the offshore wind power generation facility is assembled using this crane. The deck can also be used as a loading and unloading space for various parts of the offshore wind power generation facility.

Patent Document 1: JP 2015-37925 A Patent Document 2: JP 2016-215937 A

In recent years, offshore wind power generation facilities with large outputs, for example 6 MW or more, have been developed. As a result, the size of offshore wind power generation facilities themselves has increased, and floating facilities have been developed and put into practical use in addition to bottom-fixed types. As mentioned above, the deck of the offshore work facility is equipped with a work crane and is also used as a loading and unloading space for various parts. Therefore, in order to construct large offshore wind power generation facilities, offshore work facilities with larger decks are required. In addition, in order to construct floating wind power facilities, offshore work facilities that can work stably even in sea areas with a water depth of more than 90 m are required.

Because there are no existing self-elevating work platforms that can be used for offshore construction in waters over 90m deep, large floating cranes are usually used, but they are susceptible to the effects of waves and can lead to reduced work efficiency, such as waiting periods for work to be completed. On the other hand, offshore work facilities with large decks slow down the towing speed from the port to the sea area where the offshore facility is to be constructed. A slower towing speed causes the construction period of offshore facilities to be extended.

Therefore, one of the objectives of the present invention is to provide offshore work equipment and a manufacturing method thereof that allows stable work even in deep sea areas and can improve work efficiency.

The offshore work facility of the present invention comprises:
Three or more legs;
a deck configured as a floating structure and supported on the struts so as to be capable of ascending and descending;
a crane mounted on said deck;
having
The deck is an offshore work facility having a main deck portion on which the struts are arranged and an overhanging portion formed to overhang from the main deck portion,
the offshore work facility is configured by adding the extension portion and the crane to an existing jack-up drilling rig having the main deck portion and the pier,
The overhanging portion is attached to the main deck portion by utilizing a cantilever support structure for on-board drilling equipment mounted on the existing jack-up drilling rig;
The crane is mounted on the outrigger.

The manufacturing method of the offshore work facility of the present invention includes the steps of:
providing a jack-up drilling rig having three or more struts, a main deck section on which the struts are arranged and supported so as to be liftable relative to the struts, a cantilever supported on the main deck section via a support structure, and drilling equipment arranged on the cantilever;
removing the cantilever and the drilling equipment from the jack-up drilling rig;
The method includes attaching an extension formed by extending from the main deck section to the main deck section using the support structure; and mounting a crane to the extension section.

The present invention provides offshore work equipment that can perform stable and efficient work even in deep sea areas. In addition, the manufacturing method for offshore work equipment of the present invention allows the offshore work equipment to be manufactured in a short period of time and at low cost.

FIG. 1 is a schematic side view of an offshore work facility according to one embodiment of the present invention. FIG. 2 is a schematic plan view of the offshore work facility shown in FIG. 1 . FIG. 3 is a diagram showing an internal structure of a deck in the offshore work facility shown in FIG. 2 . FIG. 1 is a diagram illustrating the working range of a crane when the crane is placed within an area surrounded by pedestals. FIG. 11 is a schematic side view of an offshore work facility according to another embodiment of the present invention, in which the deck has a multi-layer structure. FIG. 2 is a diagram illustrating an example of a usage form of the offshore operation facility shown in FIG. 1 .

Referring to Figures 1 to 3, an offshore work facility 1 according to one embodiment of the present invention is shown, which has a strut 10, a deck 20 supported by the strut 10, and a crane 30 mounted on the deck 20. This offshore work facility 1 can be used for constructing offshore facilities such as offshore wind power generation facilities. The deck 20 is configured as a floating structure, and when constructing offshore facilities using the offshore work facility 1, the offshore work facility 1 is towed by a towing vessel such as a tugboat to the sea area where the offshore facility is to be constructed.

The struts 10 support the deck 20 above the sea surface during offshore work by the offshore work facility 1. Therefore, the struts 10 have a length that allows them to support the deck 20 above the sea surface with their lower ends resting on the seabed. The offshore work facility 1 has three or more struts 10 to stably support the deck 20. The structure of the struts 10 may be any as long as they can perform the above-mentioned functions. For example, a known structure such as a strut structure used in a self-elevating work platform or a jack-up drilling rig, which are types of offshore work facility 1, may be adopted. The length of the struts 10 is not particularly limited, but it is preferable that the struts 10 have a length that allows them to rest on the bottom and perform work stably without being affected by waves, even when working in sea areas exceeding 90 m. The cross-sectional shape of the struts 10 is also not particularly limited, and may be any shape such as a circle or a polygon.

The deck 20 is supported by a lifting mechanism (not shown) so that it can be raised and lowered freely relative to the strut 10. Any mechanism, such as a rack-and-pinion mechanism, can be used as the lifting mechanism. When towing the offshore work facility 1, this lifting mechanism is operated to raise the strut 10 relative to the deck 20 so that the strut 10 does not hit the bottom. Since the deck 20 is configured as a floating structure, the offshore work facility 1 floats on the sea surface by raising the strut 10, and in this state the offshore work facility 1 can be towed.

The deck 20 has a top wall 20a, a bottom wall 20b, and an outer peripheral wall 20c, which configures the deck 20 as a floating structure with a closed internal space. As shown in FIG. 2A, the internal space of the deck 20 is divided into multiple compartments by at least one bulkhead 20d, which is a strength member, thereby ensuring sufficient mechanical strength to use the upper surface of the deck 20 as a work space and a space for mounting parts of the offshore facility to be constructed.

2, the deck 20 has a main deck section 21, a first overhang section 22, and a second overhang section 23. In the illustrated embodiment, the deck 20 has two first overhang sections 22 and two second overhang sections 23, but the number of the first overhang sections 22 and the number of the second overhang sections 23 may be arbitrary. Of the main deck section 21, the first overhang section 22, and the second overhang section 23, the main deck section 21 is the section having the largest area when viewed from above, and the pier 10 is disposed on the outer edge of the main deck section 21. Thus, most of the upper surface of the main deck section 21 can be used as a work space and a space for mounting parts of the offshore facility to be constructed. When the offshore facility is an offshore wind power generation facility, it is preferable that the deck 20 has a space capable of mounting parts for one offshore wind power generation facility, for example. The planar shape of the main deck section 21 may be arbitrary.

When viewed from above, the first protruding portion 22 can be shaped to protrude convexly from the main deck portion 21 with respect to the side connecting two adjacent pedestals 10. It is also preferable that the upper surface of the first protruding portion 22 is configured to be on the same plane as the upper surface of the main deck portion 21. This can substantially expand the working space and component mounting space on the upper surface of the deck 20.

A crane 30 is mounted on the first overhanging portion 22. The crane 30 may be fixed or crawler type. However, since work is often performed on the first overhanging portion 22 without movement, a fixed crane 30 is sufficient in practice. In addition, a fixed crane 30 has the advantage that it occupies less space on the deck 20 compared to a crawler type crane, allowing for more space to be secured on the deck 20.

By mounting the crane 30 on the first overhanging portion 22, the crane 30 is positioned outside the area surrounded by all the piers 10 (three piers 10 in this embodiment) that support the deck 20.

In this way, by mounting the crane 30 on the first overhanging portion 22 and positioning it outside the area surrounded by the pedestals 20, the working range θ1 of the crane 30 (the rotation range around the center of rotation O of the crane 30) can be expanded to a range exceeding 180°, as shown in FIG. 2. In contrast, when the crane 30 is mounted on the main deck section 21 as shown in FIG. 3, the pedestals 10 are usually positioned at the corners of the main deck section 21, so that the crane 30 is positioned in the area between the two pedestals 10. Therefore, the working range θ2 of the crane 30 is less than 180°. By expanding the working range of the crane 30, the degree of freedom of work by the crane 30 can be improved.

If the entire deck 20 is configured as a floating structure, the first protruding portion 22 itself may or may not be configured as a floating structure. When the first protruding portion 22 is configured as a floating structure, the first protruding portion 22 can have a top wall, a bottom wall, and an outer peripheral wall that form an internal space in the first protruding portion 22, similar to the main deck 21. The first protruding portion 22 may further have a bulkhead, if necessary.

The second overhanging portion 22 is formed at a position different from the first overhanging portion 22, and overhangs from the main deck 21 in a shape that does not exceed the width of the main deck portion 21. Like the first overhanging portion 21, the second overhanging portion 22 can also be formed in a shape that overhangs convexly from the main deck portion 21 with respect to the side connecting two adjacent piers 10 when viewed from above. In addition, the second overhanging portion 22 is configured as a floating structure. Therefore, like the main deck portion 21, the second overhanging portion 22 can have a top wall, a bottom wall, and an outer peripheral wall that form an internal space in the second overhanging portion 23. The second overhanging portion 23 may further have a bulkhead, if necessary.

By adding the second overhang 23 to the main deck section 21, the space on the deck 20 is expanded, and at the same time, the stability of the offshore work facility 1 during towing can be improved. In addition, since the shape of the second overhang 23 does not exceed the width of the main deck section 21, the resistance during towing is suppressed from increasing. This allows the offshore work facility 1 to be towed efficiently, for example by suppressing a decrease in towing speed. In order to further suppress resistance during towing, when the offshore work facility 1 is configured to be towed in the direction of the white arrow shown in Figure 2A, it is preferable that the shape of the second overhang 23, which is formed by combining the main deck section 21 and the second overhang 23, is a ship shape whose width increases from the bow side to the stern side.

Although the above describes the case where the deck 20 has a single-layer structure, the deck 20 may have a multi-layer structure. Figure 4 shows a schematic side view of an offshore work facility having a multi-layer deck. In the following description of the offshore work facility shown in Figure 4, the same components as those in the offshore work facility described so far are given the same reference numerals as in Figure 1, etc., and their description will be omitted.

In the offshore work facility 1 shown in FIG. 4, the deck 20 has a second top wall 120a arranged above the top wall 20a at a distance from the top wall 20a, and a second outer peripheral wall 120c and a second bulkhead (not shown) that support the second top wall 120a at a distance from the top wall 20a, thereby giving the deck 20 a two-layer structure. The structure arranged above the top wall 20a is configured as a floating structure with an internal space divided into multiple compartments by the top wall 20a, the second top wall 120a, the second outer peripheral wall 120c, and the second bulkhead. Therefore, even if structures such as the second top wall 120a, the second outer peripheral wall 120c, and the second bulkhead are added to the top wall 20a, the deck 20 can ensure the buoyancy required to tow the offshore work facility.

The second top wall 120a and the second outer peripheral wall 120c can be arranged at a position corresponding to at least the main deck section 21 among the main deck section 21 (see FIG. 2), the first overhanging section 22 (see FIG. 2), and the second overhanging section (see FIG. 2). In other words, the entire deck 20 does not need to have a two-layer structure. However, in order to make effective use of the upper surface of the deck 20, it is preferable to arrange the second top wall 120a and the second outer peripheral wall 120c so that all areas of the main deck section 21, the first overhanging section 22, and the second overhanging section 23 have a two-layer structure.

By making the deck 20 have a two-layer structure in this way, the mechanical strength of the deck 20 can be improved, and heavier objects can be loaded onto the deck 20. As a result, when transporting parts from the construction yard for offshore facility construction to the sea area that is the construction site, the offshore work facility can be used to transport more or heavier parts. Here, the case where the deck 20 has a two-layer structure has been described, but the deck 20 can also be configured with three or more layers.

Next, a method for constructing an offshore facility using the offshore work facility 1 of this embodiment will be described using an example in which the offshore facility is an offshore wind power generation facility.

First, various parts such as the wind turbine components of the offshore wind power generation facility and the offshore work equipment 1 are moved from the construction yard to the sea area which is the construction site. The offshore work equipment 1 is moved by raising the legs 10 relative to the deck 20 and towing the offshore work equipment 1 with the deck 20 floating above the sea surface using a towing vessel. At this time, the parts of the offshore wind power generation facility are loaded onto the deck 20. If the deck 20 has enough space to load the parts for one offshore wind power generation facility and has the mechanical strength, a vessel for transporting the parts is not required to move the parts of the offshore wind power generation facility.

When the movement of the offshore wind power generation facility components and the offshore work facility 1 is complete, the piers 10 of the offshore work facility 1 are lowered toward the deck 20, and the piers 10 are seated on the seabed. At this time, as shown in FIG. 1, the piers 10 are lowered until the deck 20 is above the sea surface. This allows the offshore wind power generation facility to be constructed without being affected by oceanographic conditions.

After the strut 10 is set on the seabed, the parts on the deck 20 are suspended by the crane 30, and the offshore wind power generation equipment is assembled using the crane 30. The crane 30 is mounted on the first projection 22, which expands the working range of the crane 30 and allows for smooth assembly.

After the offshore wind power generation equipment is assembled, the struts 10 are raised again above the deck 20, and the offshore work equipment 1 is returned to the construction yard by a towing vessel.

Multiple offshore work facilities 1 can be connected and used as an offshore facility construction yard for loading and assembling offshore facility components. Figure 5 shows a plan view of a construction yard using multiple offshore work facilities 1.

The construction yard shown in Figure 5 has three offshore work facilities 1 connected together so that offshore equipment components can be loaded and assembled on the deck 20. The crane 30 is mounted on the first overhanging portion 22, ensuring more deck space. In addition, by arranging the offshore work facilities 1 so that the cranes 30 are staggered, interference between the cranes 30 is reduced even when multiple cranes 30 are operated simultaneously.

A construction yard can be set up for each project. By using the offshore work facility 1 as a construction yard, once yard work is completed, the offshore work facility 1 can be moved directly to the construction area for the offshore facility and construction of the offshore facility can be carried out. The construction yard can also be used as a permanent facility. In this way, by using the offshore work facility 1 as a construction yard, it can be used as a substitute for port facilities for offshore facilities, and the construction yard can be set up at low cost and in a short period of time.

The present invention has been described above by taking a representative embodiment as an example. The offshore work facility 1 according to the present invention can be constructed by adding a first extension 21 and a crane 30 to an existing offshore work facility such as a self-elevating work barge or a jack-up drilling rig having a main deck section 21 and piers 10, and further adding a second extension 23 as necessary. "Existing offshore work facility" means an existing offshore work facility that has already been assembled to perform the intended function of the offshore work facility, and the offshore work facility 1 according to this embodiment can be constructed by modifying such offshore work facility.

Typically, conventional offshore work equipment such as self-elevating work platforms and jack-up drilling rigs have self-elevating piers and a platform (corresponding to the main deck section 21 in the offshore work equipment 1 of this embodiment described above) that is supported so as to be able to rise and fall on the piers.

Therefore, by constructing the offshore work equipment of the present invention by utilizing (modifying) existing offshore work equipment, the struts 10 and main deck section 21 can be constructed using the struts and platform of the existing offshore work equipment structure, respectively. This makes it possible to obtain the offshore work equipment more easily and in a shorter construction period, and as a result, a significant reduction in the cost of the offshore work equipment can be achieved. In particular, by constructing the offshore work equipment 1 using an existing jack-up drilling rig, it is possible to obtain offshore work equipment that can be constructed stably without being affected by waves by landing the struts on the bottom during offshore construction in sea areas with a water depth of more than 90 m, more easily and in a shorter construction period.

Jack-up drilling rigs also have on-board drilling equipment so that they can perform drilling operations for oil and natural gas while anchored at sea. The on-board drilling equipment is mounted on a cantilever installed on a platform. However, the cantilever moves on the platform by a drive mechanism, and drilling operations are performed at a position protruding from the platform. In order to support the load of the entire cantilever, including the drive mechanism and on-board drilling equipment, the platform has strength members such as bulkheads with the necessary strength inside as a support structure.

In this embodiment, focusing on this point, when constructing the first extension portion 22, the support structure of the cantilever that the existing jack-up drilling rig has is used. That is, the first extension portion 22 is supported by the support structure of the cantilever and extends from the main deck portion 21. Here, the "support structure of the cantilever" refers to the support structure that the platform has to support the load of the entire cantilever, including the drive mechanism and the on-board drilling equipment, and specifically, a strength member, such as a bulkhead, that has the strength required to support the entire cantilever. In this way, by using the support structure that already exists in the jack-up drilling rig, the first extension portion 22 that has sufficient mechanical strength to mount a crane 30 capable of lifting a heavy structure such as a nacelle of an offshore wind power generation facility can be added more easily in accordance with the existing strength member without adding a new strength member. As a result, a significant cost reduction in the offshore work facility is achieved.

When the first extension 22 is constructed using the support structure of the cantilever of the jack-up drilling rig as described above, the cantilever of the jack-up drilling rig and the on-board drilling equipment are removed, and the first extension 22 is constructed on the support structure of the cantilever, and the crane 30 is mounted on top of it. Therefore, the offshore work facility 1 no longer functions as a drilling rig.

In addition, when the deck 20 is made into a multi-layer structure to improve the mechanical strength of the deck 20, it is generally considered to replace the existing top wall with a top wall having higher mechanical strength. However, various structures such as electrical wiring and water supply and drainage pipes are usually attached to the underside of the top wall. Therefore, when replacing the top wall, it is necessary to replace these structures as well. Therefore, as shown in FIG. 4, by leaving the top wall 20a as it is and placing the second top wall 120a above it, it is possible to utilize the existing electrical wiring and water supply and drainage pipes, etc., and as a result, it is possible to shorten the construction period of the offshore work facility 1 and suppress the increase in construction costs.

Reference Signs List 1 Offshore work facility 10 Strut 20 Deck 20a Top wall 20b Bottom wall 20c Outer periphery wall 20d Bulkhead 21 Main deck section 22 First overhanging section 23 Second overhanging section 30 Crane 120a Second top wall 120c Second outer periphery wall

Claims (4)

A jack-up drilling rig having three or more struts and a main deck portion on which the struts are arranged, from which the drilling equipment and the cantilever have been removed;
An additional structure that is added to the main deck by utilizing a cantilever support structure for on-board drilling equipment mounted on the jack-up drilling rig ;
A crane mounted on the additional structure;
An offshore work facility having the above features. The main deck section is configured as a floating structure having an internal space,
The offshore work facility according to claim 1 , wherein the internal space is divided into a plurality of spaces by bulkheads. The offshore work facility according to claim 2, wherein the additional structure is supported on the main deck section by using the bulkhead. The offshore work facility according to claim 1, wherein the main deck portion has a multi-layer structure.

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