JP2021030893A - Floating body type marine structure, floating body type offshore wind power generation system, and floating body type petroleum/gas production storage shipment system - Google Patents

Abstract

To provide a floating body type marine structure, etc., provided with an undersea long body having a floating body connected to a floating body type facility.SOLUTION: A floating body type marine structure 10 comprises: a floating body type facility 2; and an undersea long body 1 equipped with a floating body having an undersea long body 3 connected to the floating body type facility 2 and a first floating body 4 fitted to a floating body fitted part 3a of the undersea long body 3. The undersea long body 3 is configured to be able to maintain the state of floating in a sea S2 without contact with a sea bottom S1. The undersea long body 3 includes a net-like bag body 5 disposed so as to surround the outer surface of at least one of the first floating body 4 and the floating body fitted part 3a to which the first floating body 4 is not fitted. The net-like bag body 5 is characterized by being easily changed in shape, and configured to swing so as to contact with the outer surface of at least one of the floating body fitted part 3a and the first floating body 4 through flowing of sea water, thereby causing sticking of marine organisms to the surface of the floating body fitted part including the first floating body 4.SELECTED DRAWING: Figure 1

Description

The present invention relates to a floating offshore structure, for example, a floating offshore structure having a buoyant body with a buoyant body attached to an underwater cable or an underwater pipeline, and a floating offshore wind power generation system and a floating oil.・ Regarding gas production, storage and shipping system.

In recent years, from the viewpoint of global warming countermeasures, the development of so-called ocean renewable energy, which converts the natural energy of the ocean such as offshore wind power, wave power, tidal current / ocean current, etc. into electrical energy to generate electricity, has attracted attention.

Examples of offshore floating equipment (systems) that can obtain offshore renewable energy include so-called floating offshore wind power generation systems that can convert offshore wind power into electrical energy to generate electricity, and their practical application has been promoted. ing.

The floating offshore wind power generation system is configured so that the power generation wind turbine installed in the floating offshore wind turbine can be rotated by the offshore wind power and converted into electrical energy, and then the obtained power can be transmitted through an underwater cable. Has been done.

In addition, it is known that offshore floating equipment makes various movements such as three-dimensional swinging due to the flow of seawater such as tides, waves, tidal currents and ocean currents, and strong winds such as typhoons. The submarine cable is configured to follow the various movements of the offshore floating equipment. For example, in the submarine cable (submarine cable) described in Patent Document 1, an underwater intermediate buoy (buoyancy body) is attached to an intermediate portion (buoyancy body mounting portion) of the submarine cable, and the buoyancy body mounting portion of the submarine cable is attached. By the action of buoyancy by the attached buoyancy body, the part of the submarine cable other than the part where the buoyancy body is attached is curved convexly toward the sea bottom, and the entire submarine cable is curved. It is configured to have a so-called slack (slack) in an extending shape that curves in an S shape.

In addition, if there is a part of the submarine cable that has landed in contact with the seabed, the landed part repeatedly slides and moves in contact with the seabed due to the external force generated by the flow of seawater, and rubs against the seabed. Since there is a risk of damage due to this, it is desirable that the structure is such that it can be kept floating in the sea without touching the seabed.

However, as described in Patent Document 1, the submarine cable with a buoyant body in which the buoyant body is attached to the submarine cable has a normal cable installation state when it is installed while floating in the sea, and the submarine cable moves under the sea with the passage of time. After a certain period of time, the submarine cable settled (contacted) on the sea floor and moved to the bottom of the cable. If such a landing state occurs in the submarine cable, the landing part of the submarine cable may be damaged by repeatedly sliding and moving in contact with the seabed and rubbing against the seabed. However, it was necessary to maintain the normal installation state of the cable in the sea for a long period of time so that it would not settle on the seabed.

Japanese Unexamined Patent Publication No. 2015-39274

An object of the present invention is to provide an underwater long body with a buoyant body (underwater cable with a buoyant body) capable of effectively suppressing the subsidence of the underwater cable for a long period of time (for example, 20 years or more) even after being installed in the sea. To provide floating offshore structures, as well as floating offshore wind turbines and floating oil and gas production, storage and shipping systems.

As a result of diligent research on the cause of the transition from the normal installation state of the submarine cable with a buoyant body to the bottoming state of the cable in the sea, the present inventors have conducted intensive studies and found that when the submarine cable with a buoyant body is installed in the sea, the passage of time At the same time, the attachment and accumulation of marine organisms proceed on the buoyancy body mounting part of the submarine cable (long underwater body) and the surface of the first buoyancy body, so that the submarine cable moves down (settles) in the sea. By shifting to the cable bottoming state and surrounding the surface of the buoyant body mounting portion and the first buoyant body of the submarine cable with a net-like bag having predetermined characteristics in a predetermined surrounding state, the marine organisms It has been found that adhesion can be suppressed, and the present invention has been completed based on such findings.

That is, the gist structure of the present invention is as follows.
(1) A floating equipment located floating on the sea, an underwater elongated body whose one end is connected to a submarine elongated body laid on the seabed, and the other end is connected to the floating equipment, and the underwater. A submarine long body with a buoyant body having a first buoyant body mounted on a buoyant body mounted portion of the long body is provided, and the buoyant body mounted portion of the underwater long body is formed by the first buoyant body. A floating body that has an extending shape that is curved convexly toward the sea surface by the action of buoyancy, and that the long underwater body can maintain a state of floating in the sea without contacting the sea floor. In the formal marine structure, the underwater elongated body surrounds at least one outer surface of the first buoyancy body and the buoyancy body mounted portion to which the first buoyancy body is not mounted in a loose state. The buoyant bag body is further provided with a reticulated bag body arranged so as to be provided, and the reticulated bag body has a property that the shape easily changes, and at least of the buoyancy body mounting portion and the first buoyancy body due to an external force generated by the flow of seawater. A marine structure characterized in that it sways so as to come into contact with one outer surface so that marine organisms do not easily adhere to the outer surface of the portion surrounded by the reticulated bag.
(2) The first buoyant body is at least one of at least one tubular buoy and a ball-shaped buoy mounted on the buoyant body-mounted portion of the long underwater body (1). ) Described in the marine structure.
(3) The marine structure according to (1) or (2) above, wherein the net-like bag is a resin net.
(4) The underwater elongated body with a buoyant body has a length dimension in which one end is connected to the buoyant body-mounted portion of the underwater elongated body, the other end hangs down toward the seabed, and the other end reaches at least the seabed. At least one first connecting line and a plurality of first weights attached to the other end side portion of the first connecting line at intervals along the extending direction of the first connecting line. The marine structure according to any one of (1) to (3) above, which has a sedimentation prevention means.
(5) A floating offshore wind turbine located floating on the sea, an underwater cable with one end connected to a submarine cable laid on the seabed and the other end connected to the floating offshore wind turbine, and An underwater cable with a buoyancy body having a first buoyancy body attached to the buoyancy body mounting portion of the underwater cable is provided, and the buoyancy body mounting portion of the underwater cable is affected by the action of buoyancy by the first buoyancy body. In a floating offshore wind turbine system, which has an extending shape that curves convexly toward the sea surface and is configured so that the underwater cable can be maintained floating in the sea without contacting the sea floor. A mesh bag in which the underwater cable is arranged so as to surround at least one outer surface of the first buoyant body and the buoyant body mounted portion to which the first buoyant body is not mounted in a loosened state. Further comprising a body, the reticulated bag has the property of easily changing its shape so that an external force generated by the flow of seawater comes into contact with the buoyant body mounting portion and at least one outer surface of the first buoyant body. A floating offshore wind power generation system characterized in that it is configured so that marine organisms do not easily adhere to the outer surface of the portion surrounded by the reticulated bag body.
(6) Floating oil / gas production / storage / shipping facility located floating on the sea, one end is connected to the submarine pipeline laid on the seabed, and the other end is the floating oil / gas production / storage / shipment. It is provided with an underwater pipeline connected to the facility and an underwater pipeline with a buoyancy body having a first buoyancy body attached to a buoyancy body-mounted portion of the underwater pipeline, and the buoyancy body-mounted portion of the underwater pipeline is provided. The portion has an extending shape that is convexly curved toward the sea surface due to the action of buoyancy by the first buoyant body, and the underwater pipeline is maintained in a state of floating in the sea without contacting the sea floor. In a floating oil / gas production / storage / shipping system configured to be capable, the underwater pipeline is among the first buoyancy body and the buoyancy body mounted portion not equipped with the first buoyancy body. The buoyancy is further provided with a reticulated bag body arranged so as to surround at least one outer surface in a loose state, and the reticulated bag body has a property of easily changing its shape and is caused by an external force generated by the flow of seawater. It is characterized in that it swings so as to come into contact with the outer surface of at least one of the body-mounted portion and the first buoyant body so that marine organisms do not easily adhere to the outer surface of the portion surrounded by the net-like bag body. Buoyancy type oil and gas production storage shipping system.

According to the present invention, the underwater cable surrounds at least one outer surface of the first buoyant body and the buoyant body mounted portion to which the first buoyant body is not mounted in a loose state. Further provided with an arranged reticulated bag, the reticulated bag has the property of easily changing its shape and comes into contact with at least one outer surface of the buoyancy body mounting portion and the first buoyancy body by an external force generated by the flow of seawater. By being configured to prevent marine organisms from adhering to the outer surface of the part surrounded by the reticulated bag, the underwater cable can be used for a long period of time (for example, 20 years or more) even after being installed in the sea. It has become possible to provide floating offshore structures with buoyant underwater cables that can effectively control subsidence, as well as floating offshore wind turbines and floating oil and gas production storage and shipping systems.

FIG. 1 is a schematic configuration diagram of a floating offshore wind power generation system including a submarine cable with a buoyant body according to the first embodiment according to the present invention. FIG. 2 is a schematic configuration diagram of a floating offshore wind power generation system including a conventional submarine cable with a buoyant body. FIG. 3 is a diagram showing a state in which marine organisms (MG) adhere to and accumulate on the buoyant body constituting the submarine cable with a buoyant body shown in FIG. 2, and the submarine cable sinks until it bottoms on the seabed. FIG. 4 is a schematic configuration diagram of a floating offshore wind power generation system including a submarine cable with a buoyant body according to the second embodiment. FIG. 5 is a schematic configuration diagram of a floating offshore wind power generation system including a submarine cable with a buoyant body according to a third embodiment. FIG. 6 is a schematic configuration diagram of a floating offshore wind power generation system including a submarine cable with a buoyant body according to a fourth embodiment. FIG. 7 is a schematic configuration diagram of a floating oil / gas production / storage / shipping system including an underwater pipeline with a buoyant body according to a fifth embodiment. In FIG. 8, after the submarine cable with a buoyant body shown in FIG. 4 is left in the sea for 3 years, only one first buoyant body (ball-shaped buoy) and a net-like bag (resin net) surrounding the first buoyant body are removed. 8 (a) shows the outer surface state of the resin net, and FIG. 8 (b) shows the outer surface state of the ball-shaped buoy from which the resin net has been removed. FIG. 9 shows one first buoyancy after a conventional submarine cable with a buoyancy body to which a ball-shaped buoy (without a resin net) is attached is left in the sea for 3 years and the submarine cable lands in contact with the seabed. It is an external photograph when only the body (ball-shaped buoyancy) is removed and pulled up to the ground for observation.

Next, preferred embodiments of the present invention will be described below.

<First Embodiment>
FIG. 1 shows a schematic configuration of a floating offshore wind power generation system 10, which is an offshore structure of the first embodiment according to the present invention. The floating offshore wind power generation system 10 shown in FIG. 1 includes an underwater cable 1 with a buoyant body, which is a long underwater body with a buoyant body, and a floating offshore wind power generation facility 2 which is a floating offshore facility.

The illustrated submarine cable 1 with a buoyant body is connected to a submarine cable 9 which is a long submarine cable laid on the seabed S1 at one end, extends through the seabed S2, and has the other end floating on the seabed S3. It includes a submarine cable 3 which is a long undersea body connected to a buoyant offshore wind power generation facility 2 located, and a first buoyant body 4 mounted on a buoyant body mounted portion 3a of the submarine cable 3.

The floating offshore wind power generation facility 2 is in a state of floating on the seabed S3, and its lower portion is fixed to the seabed S1 with a mooring line (not shown).

The submarine cable 3 is for transmitting the electric power obtained by the floating offshore wind power generation facility 2, and is mainly composed of an electric power core, armor, an external anticorrosion layer, and the like. In the present invention, as will be described later, it is necessary that the submarine cable 3 can be deformed so as to have an extending shape that is convexly curved toward the sea surface S3 by the buoyancy F of the attached first buoyancy body 4. , It is necessary to have a certain degree of flexibility, but other structures and physical properties are not particularly limited, so various power cables with a waterproof coating that can be used in the sea should be used. Can be done.

The first buoyancy body 4 is at least one of at least one tubular buoy (FIG. 1 and the like) and a ball-shaped buoy (FIG. 4 and the like) mounted on the buoyancy body mounting portion 3a of the submarine cable 3. It is preferable to have. In the embodiment shown in FIG. 1, the first buoyant body 4 is mounted so as to cover the outer periphery of the buoyant body mounted portion 3a of the submarine cable 3 at intervals in the extending direction of the buoyant body mounted portion 3a. The case where it is composed of four tubular buoys is shown. The material of the first buoyancy body 4 may be any material that generates buoyancy to the extent that the submarine cable 3 can be maintained floating in the sea S2, and is not particularly limited. For example, the composite foam is made of polyurethane or the like. Examples include those coated with an outer skin, floats using ABS and PE resin, and the like.

The submarine cable 3 has a buoyancy body mounted portion 3a having an extending shape that is convexly curved toward the sea surface S3 due to the action of the buoyancy F by the first buoyancy body 4, and the submarine cable 3 has a submarine cable 3 on the seabed S1. It is configured so that it can be maintained floating in the sea S2 without contacting the seabed. If the submarine cable 3 is installed in the sea with the submarine cable 3 landing on the seabed S1, the landed portion of the submarine cable may be damaged by repeatedly sliding and moving in contact with the seabed and rubbing against the seabed. On the other hand, if the buoyancy body mounting portion 3a of the submarine cable 3 exists at the height position of the sea surface S3 or the height position of the sea S2 close to the sea surface S3, it may come into contact with the ship 11 or the like navigating the sea. There is a risk of hindering the navigation of the ship and, in some cases, damage to the submarine cable due to contact with the ship or the like.

A suitable submarine installation depth region including an S-shaped curved extending shape of a mountain (top) and a valley (valley bottom) of the submarine cable 3 floating in the sea S2 is from the seabed S1 to the sea surface S3. A depth position (undersea lower limit depth line) preferably 10 m or more, more preferably 15 m or more away in the vertical direction toward the sea surface (opposite to the water depth direction), and preferably 10 m or more, more preferably 15 m or more from the sea surface S3. It is an underwater area separated by a distant depth position (upper seafloor depth line). In particular, in the underwater cable 3, the floating offshore wind power generation system and the ship have the fact that the mountain portion (top) of the buoyant body mounting portion 3a curved in a convex shape is in the sea at the depth position from the sea surface S3. It is preferable in that it avoids a floating offshore wind power generation system from contact with the wind turbine. Further, it is preferable that the submarine cable 3 has a valley (valley bottom) position in the sea at the above-mentioned depth position from the viewpoint of avoiding the landing of the submarine cable on the seabed. The submarine cable 3 is installed in the submarine S2 whose deepest part is deeper than, for example, 100 m or more.

In the present inventors, the conventional submarine cable with a buoyant body as described in Patent Document 1 moves downward (settles) in the sea with the passage of time, and after a certain period of time, the submarine cable is released. We investigated in detail the cause of the transition to a landing state in which the seabed subsides (contacts).

By the way, marine organisms such as Fujitsubo (Marine Growth, hereinafter may be abbreviated as "MG") are almost always present in the marine structures existing on the sea surface S2 and the sea surface S3 near the sea surface S3. It is easy to adhere, and there are various types of MG, and it has a mass of large and small and light and heavy.

Therefore, regarding the transition of the submarine cable 3 to the bottomed state, when the submarine cable 1 with a buoyant body is installed in the sea, the present inventors attach the marine organism 105 to the surface of the submarine cable 1 with a buoyant body. We conducted a diligent study under the hypothesis that it would move down in the sea due to this. As a result, the submarine cable 1 with a buoyant body installed in the sea is attached to and deposited on the buoyant body-mounted portion 3a of the submarine cable 3 to which the first buoyant body 4 and the first buoyant body 4 are mounted. When the 105 moves the submarine cable 3 of the submarine S2 downward with the lapse of the cable installation period in the submarine S2, and when the cable installation period reaches several years or more (for example, three years or more), the Fujitsubo exceeds expectations. It has been found that the submarine cable 3 may land on the bottom due to the attachment of marine organisms such as 105.

More specifically, in the conventional underwater cable 101 with a buoyant body, the buoyant body 104 is attached to the portion to which the buoyant body is attached, and in the normal installation state of the cable in the underwater S2, as shown in FIG. 2, the seabed S1 It is configured so that it can maintain a state of floating in the sea S2 without contacting the seabed.

However, in the underwater cable 103, the attachment / deposition of the marine organism 105 progresses on the surfaces of the buoyancy body 104 and the underwater cable 103 with the passage of time, and the attachment / deposition of the marine organism 105 causes the buoyancy body of the underwater cable 103. Since the weight of the mounted portion becomes heavy and a large gravity acts on the underwater cable 103, the buoyancy by the buoyancy body 104 is reduced. As a result, the entire submarine cable 103 will settle toward the seabed S1, and further, as the adhesion and deposition of the marine organism 105 on the surfaces of the buoyant body 104 and the submarine cable 103 proceed, as shown in FIG. The present inventors have found that the submarine cable 103 tends to come into contact with the seabed S1 and land on the seabed after shifting to the cable bottoming state.

Further, in order to prevent marine organisms from adhering to the submarine cable 3, a method of containing / coating cuprous oxide, an arsenic compound, an organic tin compound or the like on the outer surface of the submarine cable 3 is also conceivable. However, the effect of such a method is limited, it cannot be exerted for a long period of time, and it is difficult to use it due to environmental problems.

Therefore, as a result of diligent studies to prevent the marine organisms 105 from adhering to the submarine cable 3 in an environmentally friendly manner, the present inventors have conducted diligent studies to achieve the buoyancy body mounting portion 3a and the first buoyancy body 4 of the submarine cable 3. It has been found that the adhesion of marine organisms 105 can be effectively suppressed by surrounding the surface of the sea with a net-like bag body 5 having predetermined characteristics in a predetermined surrounding state.

That is, in the present invention, the underwater cable 3 surrounds at least one outer surface of the first buoyancy body 4 and the buoyancy body mounted portion 3a to which the first buoyancy body 4 is not mounted in a loose state. The buoyant body 5 is further provided with the buoyant body 5 arranged in the above, and the buoyant body 5 has a property that the shape easily changes, and at least one of the buoyancy body mounting portion 3a and the first buoyancy body 4 due to an external force generated by the flow of seawater. It is configured so that the marine organism 105 does not easily adhere to the outer surface of the portion surrounded by the net-like bag body 5 by swaying so as to come into contact with the outer surface of the body. As a result, the submarine cable 3 can be effectively suppressed from settling for a long period of time even after the submarine cable 3 is installed in the submarine S2.

The net-like bag body 5 surrounds at least one outer surface of the first buoyancy body 4 and the buoyancy body-mounted portion 3a of the underwater cable 3 to which the first buoyancy body 4 is not mounted in a loose state. It has the property of being arranged and easily changing in shape, and is configured to swing so as to come into contact with at least one outer surface of the buoyancy body mounting portion 3a and the first buoyancy body 4 by an external force generated by the flow of seawater. It is necessary.

When the net-like bag body 5 is arranged so as to surround the first buoyancy body 4 or the like in close contact with the outer surface, the portion of the net-like bag body 5 becomes the outer surface of the first buoyancy body 4 or the like due to the external force generated by the flow of seawater. On the other hand, since it cannot swing, it is not possible to prevent the marine organism 105 from adhering to the outer surface of the first buoyant body 4 or the like. By surrounding the net-like bag body 5 in a loose state with respect to the outer surface of the first buoyancy body 4, etc., the net-like shape is generated by the external force generated by the seawater flow (natural flow) such as tides, waves, tidal currents, and sea currents. The portion of the bag body 5 swings in a free motion to change its shape, and repeatedly contacts and separates from the outer surface of the buoyancy body 4 and the buoyancy body mounting portion 3a of the underwater cable 3, so that the marine organism 105 with respect to the buoyancy body 4 and the like Can be effectively prevented from adhering.

Further, by surrounding the first buoyancy body 4 and the like with the mesh bag body 5, the mesh of the mesh bag body 5 blocks light energy such as ultraviolet rays and creates a shadow on the outer surface of the enclosed first buoyancy body 4 and the like, and the ocean. Since the photosynthesis of the organism is suppressed, the adhesion of the marine organism 105 to the buoyant body 4 and the like can be effectively prevented.

Further, since the net-like bag body 5 surrounding the buoyancy body 4 and the like swings, the flow of seawater passing through the mesh of the net-like bag body 5 and reaching the outer surface of the buoyancy body 4 and the like becomes turbulent. , The adhesion of the marine organism 105 to the buoyant body 4 and the like can be effectively prevented.

The material of the net-like bag body 5 may have a property that the shape can be easily changed by an external force generated by the flow of seawater, and is not particularly limited, and examples thereof include a resin net.

As a method of mounting the net-like bag body 5 on the buoyancy body-mounted portion 3a and the first buoyancy body 4 of the underwater cable 3, as shown in FIG. It may be attached by tying both open ends of the bag body 5 with a binding band or a rope. In addition, the reticulated bag body 5 may be formed by covering the first buoyant body 4 or the like so as to surround the reticulated body in a loosened state and then binding the reticulated body with a binding band, a rope, or the like. The reticulated bag body 5 may be formed by wrapping the reticulated body around the body 4 or the like so as to surround the reticulated body in a loose state.

As described above, the submarine cable 1 with a buoyant body of the first embodiment can be maintained for a long period of time because the net-like bag body 5 can suppress the adhesion of marine organisms (MG) to the first buoyant body 4 and the like. Even if this is not done, the submarine cable 3 will not land on the bottom.

<Second embodiment>
FIG. 4 shows a schematic configuration of a floating offshore wind power generation system 10A including a submarine cable 1A with a buoyant body according to a second embodiment according to the present invention. When the constituent members shown in FIG. 4 are the same as the constituent members shown in FIG. 1, they are designated by the same reference numerals.

The floating offshore wind power generation system 10A of the second embodiment has the same configuration as the floating offshore wind power generation system 10 of the first embodiment, except that the configuration of the first buoyant body is different. Therefore, the configuration of the first buoyant body 4A will be described below.

In the present embodiment, a ball-shaped buoy 4A is used as the first buoyancy body, and in FIG. 4, four ball-shaped buoys surrounded by a net-like bag body 5 are attached to the buoyancy body-mounted portion 3a of the submarine cable 3. The case where the buoy 4A is attached at an interval is shown.
The method of mounting the mesh bag body 5 on the buoyancy body mounting portion 3a and the first buoyancy body 4A of the submarine cable 3 is the same as the mounting method of the mesh bag body 5 in the first embodiment.

<Third embodiment>
FIG. 5 shows a schematic configuration of a floating offshore wind power generation system 10B including a buoyant submarine cable 1B according to a third embodiment according to the present invention. When the constituent members shown in FIG. 5 are the same as the constituent members shown in FIGS. 1 and 4, they are designated by the same reference numerals.

The floating offshore wind power generation system 10B of the third embodiment includes a floating offshore wind power generation facility 2 and an underwater cable 1B with a buoyancy body, and a first buoyancy body is attached to a buoyancy body mounting portion 3a of the underwater cable 3. As a result, both the tubular buoy 4 and the ball-shaped buoy 4A are mounted, and the two outer surfaces of the buoyancy body mounted portion 3a on which the buoyancy bodies 4 and 4A are not mounted are surrounded by the mesh bag body 5 in a loosened state. The other configurations are the same as those of the floating offshore wind power generation system 10 of the first embodiment. Hereinafter, a configuration different from that of the floating offshore wind power generation system 10 of the first embodiment will be described.

In the third embodiment, both the tubular buoy 4 and the ball-shaped buoy 4A are used as the first buoyancy body, and in FIG. 5, the buoyancy body mounting portion 3a of the submarine cable 3 is spaced apart from each other. In addition to mounting four tubular buoys 4, four ball buoys are mounted between the tubular buoys 4, 4, and a total of eight buoys 4, 4A and buoys 4, 4A. It shows the case where the two parts of the buoyancy body mounted portion 3a on which the buoyancy body is not mounted are mounted with the net-like bag body 5 that individually surrounds the two portions.

The types and number of arrangements of the first buoyancy bodies 4 and 4A and the number of arrangements of the net-like bag 5 can be determined as necessary. In particular, from the viewpoint of effectively preventing the contact (landing) of the submarine cable 3 with the seabed S1 due to the adhesion of the marine organism 105, the buoyancy body mounting portions 3a of the first buoyancy bodies 4 and 4A and the submarine cable 3 It is preferable to arrange the net-like bag body 5 so as to cover as much as possible.

<Fourth Embodiment>
FIG. 6 shows a schematic configuration of a floating offshore wind power generation system 10C including a submarine cable 1C with a buoyant body according to a fourth embodiment according to the present invention. When the constituent members shown in FIG. 6 are the same as the constituent members shown in FIGS. 1, 4 and 5, they are designated by the same reference numerals.

In the fourth embodiment, the submarine cable 1C with a buoyant body increases in weight at the buoyant body mounting portion 3a of the submarine cable 3 due to the marine organism (MG) 105 adhering to the surface of the first buoyant body 4. The submarine cable 3 is further provided with a settling prevention means 6 for preventing the cable 3 from settling and coming into contact with the seabed S1.

In the fourth embodiment, the settling prevention means 6 is mainly composed of at least one first connecting line 7 and a plurality of first weights 8, and in FIG. 6, the four first connecting lines 7 are formed. A case is shown in which each of the first connecting lines 7 is composed of 12 first weights 8. Further, FIG. 6 shows a case where the same 12 first weights 8 are attached to the first connecting wires 7 and are used, but different sizes and weights should be used. Can be done. For example, in the first weight 8 which has landed from the beginning (6 out of 12 in FIG. 6 are grounded), the submarine cable 3 is underwater by the first buoyant body 4. In order to fix S2 so as not to move upward, a weight heavier than the other first weight 8 may be used. The other first weight 8 did not land on the seabed S1 immediately after the underwater cable 3 was installed in the sea, and the first connecting line 7 was more than the first weight 8 that had landed from the beginning. It is a weight attached to a part on one end side (sea surface S3 side).

One end of the first connecting line 7 is connected to the buoyancy body mounting portion 3a of the underwater cable 3, hangs down toward the seabed S1, and the other end has a length dimension that reaches at least the seabed S1.

A plurality of first weights 8 are attached to the other end side of the first connecting line 7 at intervals along the extending direction of the first connecting line 7, and in FIG. 6, twelve first weights 8 are attached. Is shown in the case where is connected to the so-called balance chain (balance weight) method.

The submarine cable 1 with a buoyant body provided with such a settling prevention means 6 has the settling prevention means 6 even if the marine organism (MG) 105 adheres to or accumulates on the submarine cable 3 or the first buoyant body 4. By providing the above, it is possible to maintain the state of floating in the seabed S2 for a long period of time without landing on the seabed S1.

The mechanism will be described below. In order to make the explanation easier to understand, the buoyancy F acting on the submarine cable 3 is set to 1000 kgf (9.8 kN) by the first buoyancy body 4 attached to the submarine cable 3, and the settling prevention means 6 is set to one first buoyancy body 6. 1 It shall consist of a connecting wire 7 and 12 first weights 8 (6 of the 12 first weights 8 shall be in a state of being bottomed from the beginning of the underwater installation of the submarine cable). Further, twelve first weights 8 are attached to the other end side of the first connecting wire 7 at intervals of 42 cm along the extending direction of the first connecting wire 7, and the twelve first weights 8 are attached. _{When the total weight W 12} of the weight 8 of 1 is 2000 kgf (19.6 kN), the cable initial setting (normal) state is set, and from this state, the marine organism 105 adheres to the first buoyant body 4 and the submarine cable 3. Let's assume the case of going on. In this case, the total weight of the buoyancy F acting on the submarine cable 3 by the first buoyancy body 4 and the six non-grounded first weights 8 of the sedimentation prevention means 6 is 1000 kgf (9.8 kN). Balanced (balanced). For convenience, the above configuration is an example for explaining the mechanism, and the installation conditions of the first buoyancy body 4 and the sedimentation prevention means 6 are appropriately changed according to the ocean conditions such as the depth of the seabed and the flow of seawater. May be good.

In this case, the marine organism (MG) 105 adheres to the first buoyancy body 4 and the submarine cable 3, and the attached weight w of the MG is about 167 kgf, which is the weight corresponding to one of the first weights 8. When it reaches (about 1.63N), the balance between the buoyancy F generated in the submarine cable 3 by the first buoyancy body 4 and the total weight W ₆ of the six first weights 8 that have not landed is lost. The submarine cable 3 will move down in the sea. However, when the submarine cable 3 moves downward by 42 cm, the result is that the first weight 8 located closest to the seabed S1 out of the six first weights 8 that have not landed. , The total weight of the buoyancy F, the total weight W ₅ of the first weights 8 for five pieces, and the attached weight w of the MG become the same, and the weight can be balanced. Is suppressed.

After that, when the adhered weight w of MG further increases by 167 kgf, the submarine cable 3 further descends by 42 cm, but as a result, the second weight 8 located on the seabed S1 side bottoms out. and buoyancy F, 4 pieces of the first total weight W ₄ of the weight 8 and MG weight deposited 2w total weight and becomes the same in, since it becomes take the weight balance, downward movement of the underwater cable 3 Is suppressed.

In this way, every time the adhered weight w of MG increases by 167 kgf, the submarine cable 3 moves downward by 42 cm, but every time one of the first weights 8 located on the seabed side that has not grounded has landed. In addition, since the downward movement of the submarine cable 3 is suppressed, the submarine cable 3 can be suppressed from landing on the seabed S1 for a long period of time.

There is a limit to the amount of marine organisms 105 that can be attached / deposited to the first buoyancy body 4 and the underwater cable 3, and when the amount of attachment / accumulation of marine organisms 105 reaches the limit, of the attached marine organisms 105. Part of it will come off from the surface of the first buoyant body 4 and the underwater cable 3. In this case, the weight balance is lost, and the submarine cable 3, particularly the buoyancy body mounting portion 3a, suddenly shifts to the ascending movement of the underwater S2, but when it moves upward, the first one that has landed. As a result of the weight 8 being lifted to the underwater S2 again to balance the weight, abnormal ascending movement is suppressed. Therefore, the submarine cable 3 has a relatively small downward and upward movement displacement (vertical swing width) in the undersea S2, and can maintain a relatively stable state of floating in the sea.

As described above, the submarine cable 1C with a buoyant body of the fourth embodiment can automatically repeat the descending movement and the ascending movement according to the adhesion state of the marine organism 105 to the first buoyant body 4, so that it can be moved for a long period of time. Over the course, the submarine cable 3 will not land on the ground even if maintenance is not performed.

<Fifth Embodiment>
FIG. 7 shows a schematic configuration of a floating oil / gas production / storage / shipping system 30 including an underwater pipeline 21 with a buoyant body according to a fifth embodiment.
The floating oil / gas production / storage / shipping system 30 shown in FIG. 7 includes an underwater pipeline 21 with a buoyancy body, which is a long underwater body with a buoyancy body, and a floating oil / gas production / storage / shipping facility, which is an offshore floating body facility. It has 22 and.

The illustrated undersea pipeline 21 with a buoyant body is connected to a submarine pipeline 29, which is a long submarine body laid on the seabed S1 at one end, extends through the seabed S2, and floats at the other end on the seabed S3. The underwater pipeline 23, which is an underwater long body connected to the floating oil / gas production storage / shipping facility 22 located in the state, and the first buoyancy body mounted on the buoyancy body mounting portion 23a of the undersea pipeline 23. It has 24 and.

The floating oil / gas production / storage / shipping facility 22 is in a state of floating on the seabed S3, and its lower portion is fixed to the seabed S1 with a mooring line (not shown). The floating oil / gas production / storage / shipping facility 22 shown in FIG. 7 is a ship-type floating oil / gas production / storage / shipping facility (FPSO), and is a deck called the top side equipped with a hull and production facilities. It is composed of parts.

The undersea pipeline 23 is a pipeline for transporting a fluid containing a hydrocarbon resource pulled up from the seabed S1 to a floating oil / gas production storage / shipping facility 22 via a seabed pie line 29. In the present invention, as will be described later, it is necessary that the underwater pipeline 23 can be deformed so as to have an extending shape that is convexly curved toward the sea surface S3 by the buoyancy F of the attached first buoyancy body 24. Therefore, it is necessary to have a certain degree of flexibility, but since other structures and physical properties are not particularly limited, various pipes that can be used in the sea can be used.

As the first buoyancy body 24, the same ones as the first buoyancy bodies 4 and 4A described in the first to fourth embodiments can be used.

Similarly to the submarine cables 1, 1A, 1B, and 1C with buoyancy shown in the first to fourth embodiments, the buoyancy body-mounted portion 23a of the submarine pipeline 23 has a first buoyancy. By the action of the buoyancy F by the body 24, it has an extending shape that is convexly curved toward the sea surface S3, and the underwater pipeline 23 can maintain a state of floating in the sea S2 without contacting the seabed S1. It is configured in. When the underwater pipeline 23 is installed in the sea with the landing on the seabed S1, the landed portion of the underwater pipeline 23 repeatedly slides and moves in contact with the seabed and rubs against the seabed. On the other hand, if the buoyant body mounting portion 3a of the underwater pipeline 23 exists at the height position of the sea surface S3 or the height position of the sea S2 close to the sea surface S3, the vessel 11 or the like navigating the sea may be damaged. There is a possibility that it may interfere with the navigation of the ship, and in some cases, the contact with the ship or the like may damage the underwater pipeline.

The underwater installation depth region of the underwater pipeline 23 floating in the underwater S2, which includes the S-shaped curved extending shape of the mountain (top) and the valley (valley bottom), is from the seabed S1 to the sea level S3. In the vertical direction (opposite to the water depth direction), for example, preferably 10 m or more, more preferably 15 m or more away from the depth position (undersea lower limit depth line), and from the sea level S3, for example, preferably 10 m or more, more preferably. May be an underwater area partitioned by a depth position (underwater upper limit depth line) separated by 15 m or more. In the submarine pipeline 23, when the mountain portion (top) of the buoyant body mounting portion 3a curved in a convex shape is in the sea at the depth position from the sea surface S3, the floating offshore wind power generation system comes into contact with the ship. When the valley (valley bottom) position is in the sea at the above depth position, there is a tendency to suppress the landing of the underwater cable on the seabed.

In the floating oil / gas production / storage / shipping system 30 of the fifth embodiment, the underwater pipeline 23 is among the first buoyancy body 24 and the buoyancy body mounted portion 23 to which the first buoyancy body 24 is not mounted. Further, the mesh bag body 25 is further provided with at least one outer surface arranged so as to surround the outer surface in a loose state, and the mesh bag body 25 has a property of easily changing its shape and is buoyant due to an external force generated by the flow of seawater. It is configured to swing so as to come into contact with at least one outer surface of the body-mounted portion 23a and the first buoyancy body 24 so that marine organisms do not easily adhere to the outer surface of the portion surrounded by the net-like bag body 25. The effect of adopting such a configuration in the floating oil / gas production / storage / shipping system 30 of the fifth embodiment is that the floating offshore wind power generation systems 10 and 10A of the first to fourth embodiments described above are effective. Since the effects are the same as those described in 10C, the description thereof will be omitted.

Finally, in order to explain the effect of the present invention, as an example, the conventional submarine cable with a buoyant body (conventional example) and the submarine cable 1A with a buoyant body of the second embodiment (example) are attached to the underwater S2. The condition after being left for 3 years has been investigated and will be explained below.

FIG. 8 shows one first buoyant body (ball-shaped buoy) 4A and a net shape surrounding the first buoyant body (ball-shaped buoy) 4A after the submarine cable 1A with a buoyant body (FIG. 4) of the second embodiment is left in the sea S2 for 3 years. It is an external photograph when only the bag body (resin net) 5 is removed and pulled up to the ground and observed. FIG. 8 (a) shows the outer surface state of the resin net 5, and FIG. 8 (b) shows the resin net 5. The outer surface state of the ball-shaped buoy 4A from which the above is removed is shown. The submarine cable 1A with a buoyant body was maintained in a floating state within an appropriate underwater depth setting region until the first buoyant body 4A was removed.

In FIG. 9, a conventional submarine cable with a buoyant body to which a ball-shaped buoy (without a resin net) is attached is left in the sea S2 for 3 years, and then only one first buoyant body (ball-shaped buoy) is removed and placed on the ground. It is an external photograph when it is pulled up and observed.

As is clear from the external photographs shown in FIGS. 8 and 9, in the conventional submarine cable with a buoyant body, a large number of marine organisms are attached and deposited on the buoyant body (ball-shaped buoy). On the other hand, in the submarine cable 1B with a buoyant body of the embodiment, since the first buoyant body (ball-shaped buoy) is surrounded by a net-like bag body (resin net) in a loosened state, adhesion of marine organisms is almost recognized. I couldn't.

Although some embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, but includes all aspects included in the concept of the present invention and the scope of claims, and is the scope of the present invention. It can be modified in various ways within.

1, 1A, 1B, 1C Submarine long body with buoyant body (or submarine cable with buoyant body)
2 Offshore floating equipment (or floating offshore wind power generation equipment)
3 Submarine long body (or submarine cable)
3a Buoyant body mounted part of long underwater body 4 1st buoyant body (or tubular buoy)
4A ball-shaped buoy 5 net-like bag body 6 settling prevention means 7 first connecting line 8 first weight (or balance chain)
9 Submarine long body (or submarine cable)
10, 10A, 10B, 10C Floating offshore structures (or floating offshore wind turbines)
21 Underwater pipeline with buoyant body 22 Floating oil and gas production storage and shipping equipment 23 Underwater pipeline 24 1st buoyant body 25 Reticulated bag body 26 Settlement prevention means 27 1st connecting line 28 1st weight (or balance chain)
29 Submarine pipeline 30 Floating oil and gas production storage and shipping system 100 Floating offshore wind power generation system 101 Floating offshore wind turbine 102 Floating offshore wind turbine 103 Underwater cable 104 First buoyant body 105 Marine life (MG)
S1 Seabed S2 Underwater S3 Sea (sea level)

Claims (6)

Offshore floating equipment located floating on the sea and
A first buoyancy mounted on a buoyancy body-mounted portion of an underwater elongated body, one end of which is connected to a submarine elongated body laid on the seabed and the other end of which is connected to the offshore floating body facility. Equipped with an underwater long body with a buoyant body that has a body,
The buoyant body-mounted portion of the underwater elongated body has an extending shape that is convexly curved toward the sea surface due to the action of buoyancy by the first buoyant body, and the underwater elongated body is the seabed. In a floating marine structure that is configured to remain floating in the sea without contacting
A net-like structure in which the underwater elongated body is arranged so as to surround at least one outer surface of the first buoyant body and the buoyant body mounted portion to which the first buoyant body is not mounted in a loosened state. With more bags,
The net-like bag has a property of easily changing its shape, and is shaken by an external force generated by the flow of seawater so as to come into contact with at least one outer surface of the buoyancy body mounting portion and the first buoyancy body. A floating marine structure characterized in that marine organisms are less likely to adhere to the outer surface of the portion surrounded by the reticulated bag. The first buoyancy body according to claim 1, wherein the first buoyancy body is at least one of at least one tubular buoy and a ball-shaped buoy mounted on the buoyancy body mounting portion of the long underwater body. Floating offshore structure. The floating marine structure according to claim 1 or 2, wherein the net-like bag is a resin net. The underwater long body with a buoyant body is
At least one first connecting line having a length dimension such that one end is connected to the buoyant body mounting portion of the long underwater body, the other end hangs down toward the seabed, and the other end reaches at least the seabed.
Claims 1 to 1, further comprising a settling prevention means having a plurality of first weights mounted at intervals along the extending direction of the first connecting line at the other end side portion of the first connecting line. The floating offshore structure according to any one of 3. Floating offshore wind turbines located floating on the sea
One end is connected to a submarine cable laid on the seabed, and the other end is an underwater cable connected to the floating offshore wind power generation facility, and a first buoyant body mounted on a buoyant body mounted portion of the undersea cable. Equipped with a submarine cable with a buoyant body,
The buoyant body-mounted portion of the submarine cable has an extending shape that is convexly curved toward the sea surface due to the action of buoyancy by the first buoyancy body, and the submarine cable does not come into contact with the seabed. In a floating offshore wind turbine that is configured to remain floating in the sea
A net-like bag in which the submarine cable is arranged so as to surround at least one outer surface of the first buoyant body and the buoyant body mounted portion to which the first buoyant body is not mounted in a loosened state. With more
The net-like bag has a property that its shape easily changes, and is swayed by an external force generated by the flow of seawater so as to come into contact with the buoyant body mounting portion and at least one outer surface of the first buoyant body. A floating offshore wind power generation system characterized in that marine organisms are less likely to adhere to the outer surface of the part surrounded by the reticulated bag. Floating oil and gas production, storage and shipping facilities located floating on the sea
One end is connected to the submarine pipeline laid on the seabed, and the other end is attached to the submarine pipeline connected to the floating oil / gas production storage and shipping facility, and the buoyancy body mounting portion of the submarine pipeline. It is equipped with an underwater pipeline with a buoyant body that has a first buoyant body.
The portion of the underwater pipeline to which the buoyancy body is attached has an extending shape that is convexly curved toward the sea surface due to the action of buoyancy by the first buoyancy body, and the underwater pipeline comes into contact with the seabed. In a floating oil and gas production, storage and shipping system that is configured to remain floating in the sea without
A mesh bag in which the underwater pipeline is arranged so as to surround at least one outer surface of the first buoyant body and the portion to which the first buoyant body is not mounted in a loose state. Equipped with more body
The net-like bag has a property that its shape easily changes, and is swayed by an external force generated by the flow of seawater so as to come into contact with the buoyant body mounting portion and at least one outer surface of the first buoyant body. A floating oil / gas production / storage / shipping system characterized in that marine organisms are less likely to adhere to the outer surface of the part surrounded by the net-like bag.