EP4198203A1 - Procédé d'ancrage d'une plateforme flottante sur un fond rocheux - Google Patents

Procédé d'ancrage d'une plateforme flottante sur un fond rocheux Download PDF

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Publication number
EP4198203A1
EP4198203A1 EP21306851.3A EP21306851A EP4198203A1 EP 4198203 A1 EP4198203 A1 EP 4198203A1 EP 21306851 A EP21306851 A EP 21306851A EP 4198203 A1 EP4198203 A1 EP 4198203A1
Authority
EP
European Patent Office
Prior art keywords
line
grout
trench portion
core
plates
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP21306851.3A
Other languages
German (de)
English (en)
Inventor
Benoit CAILLET
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
TotalEnergies Onetech SAS
Original Assignee
TotalEnergies Onetech SAS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by TotalEnergies Onetech SAS filed Critical TotalEnergies Onetech SAS
Priority to EP21306851.3A priority Critical patent/EP4198203A1/fr
Priority to KR1020247024401A priority patent/KR20240119337A/ko
Priority to PCT/EP2022/086741 priority patent/WO2023117966A1/fr
Publication of EP4198203A1 publication Critical patent/EP4198203A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B21/00—Tying-up; Shifting, towing, or pushing equipment; Anchoring
    • B63B21/24—Anchors
    • B63B21/26—Anchors securing to bed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B21/00—Tying-up; Shifting, towing, or pushing equipment; Anchoring
    • B63B21/24—Anchors
    • B63B21/26—Anchors securing to bed
    • B63B21/29—Anchors securing to bed by weight, e.g. flukeless weight anchors
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D27/00—Foundations as substructures
    • E02D27/32—Foundations for special purposes
    • E02D27/52—Submerged foundations, i.e. submerged in open water
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D27/00—Foundations as substructures
    • E02D27/32—Foundations for special purposes
    • E02D27/52—Submerged foundations, i.e. submerged in open water
    • E02D27/525—Submerged foundations, i.e. submerged in open water using elements penetrating the underwater ground
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B21/00—Tying-up; Shifting, towing, or pushing equipment; Anchoring
    • B63B21/24—Anchors
    • B63B21/26—Anchors securing to bed
    • B63B2021/262—Anchors securing to bed by drag embedment
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2250/00—Production methods
    • E02D2250/0061—Production methods for working underwater

Definitions

  • the present invention deals with a process of anchoring a floating platform on a rocky seabed, comprising connecting a mooring steel chain to a connecting point and to the platform.
  • Drilled and grouted piles usually have a 3m diameter. Installing them requires digging a 20m deep hole, and filling the annulus between the pile and the rock with grout. They require investigating the seabed over a depth of more than 20m.
  • the solution of drilled and grouted piles is in fact very challenging for water depths where jack-ups cannot be jacked, e.g. for water depths over 60m.
  • drilling is subject to risks, such as weather and ocean conditions, and technical problems such as hole collapse, very hard rock, management of cuttings....
  • the number of drilling contractors is quite limited in the world.
  • Gravity based structures filled with sand and gravel represent an alternative. However, they lead to large structures occupying a surface of about 20m x 20m. They require thousands of tons of sand or gravel for ballasting. In the end, they are also quite expensive, and have a non-negligible environmental footprint because of their footprint and influence over the water column.
  • An aim of the invention is to provide an anchoring process adapted to a rocky seabed allowing reducing costs and environmental footprint.
  • the invention proposes a process of anchoring a floating platform on a rocky seabed, comprising the following steps:
  • the process comprises one or several of the following features, taken in isolation or any technically feasible combination:
  • the invention also deals with an anchoring system adapted for anchoring a floating platform on a rocky seabed, the anchoring system comprising:
  • the anchoring system 10 is adapted for anchoring a floating platform 12 (symbolized by a square in Figure 1 ) to a rocky seabed 14.
  • rocky it is meant here that the seabed 14 comprises rocks 16, to which the anchoring system is fixed.
  • the strength of the anchoring system depends on the strength of rock (from very weak to very strong) and the level of fracturation (from highly weathered/fractured (Rock Quality Designation: worse) to no weathered/fractured (Rock Quality Designation: excellent).
  • the platform 12 for example hosts a wind turbine (not shown).
  • the platform 12 floats on a body of water 18 (see, ocean or lake) extending over the seabed 14.
  • the anchoring system 10 comprises a trench portion 20 located in the seabed 14 and extending along a line L, an anchor structure 22 located in the trench portion, grout 24 located in the trench portion, and a mooring steel chain 26 connected to the platform 12 and to a connecting point 28 of the anchor structure.
  • the anchoring system 10 is advantageously designed to resist efforts F applied by the mooring chain 26 on the anchor structure 22, for example up to 10000kN.
  • the anchoring system 10 is advantageously designed to have a lifespan of at least 25 years.
  • said efforts F apply compression to the anchor structure 22 along the line L.
  • the line L is advantageously straight.
  • the line L follows the seabed 14 and is for example horizontal in case of a flat seabed.
  • a transverse direction T is also defined as perpendicular to the line L and horizontal.
  • the line L may be inclined in order to follow a seabed with a gentle slope.
  • the efforts F are for example parallel to the seabed 14 (case of a catenary mooring system).
  • a portion 30 of the mooring chain 26, extending from the connecting point 28, lies on the seabed 14 and/or on the grout 24.
  • the portion 30 and the line L advantageously define an angle ⁇ smaller than 30°, and preferably smaller than 10°. This means that most of the efforts F are exerted on the anchor structure 22 along the line L.
  • the mooring chain 26 does not have a portion 30 lying on the seabed 14 and/or on the grout 24, and defines an angle ⁇ with a horizontal plan at the connecting point 28. This may happen when the efforts F are large.
  • the angle ⁇ remains smaller than 10°.
  • the trench portion 20 may be natural, from previous digging, or preferably from dedicated digging.
  • the trench portion 20 for example has a U-shaped or V-shaped section 32 perpendicularly to the line L.
  • the trench portion 20 for example has a length L1 along the line L comprised between 5.0m and 40m, advantageously between 10m and 30m.
  • the trench portion 20 for example has an average horizontal width L2 perpendicularly to the line L, said width being comprised between 0.3m and 2.5m, advantageously between 0.5m and 2.0m.
  • the trench portion 20 for example has an average depth L3 comprised between 1.0m and 5.0m, advantageously between 1.0m and 2.5m.
  • the anchor structure 22 comprises a core 34 extending along the line L, steel plates 36 welded to the core and extending from the core radially with respect to the line L, and two grout lines 38, 40 extending along the line L.
  • the anchor structure 22 only has one grout line, or includes more than two grout lines.
  • the anchor structure 22 is entirely located in the trench portion 20. In other words, the anchor structure 22 is below the seabed level.
  • the anchor structure 22 advantageously extends over more than 90% of the trench portion 20 along the line L.
  • the anchor structure 22 is advantageously fully surrounded by the grout 24 around the line L.
  • the grout aims at ensuring a sealing of the anchor structure 22 with the surrounding seabed 14.
  • the core 34 consists of a steel H-beam 42 extending along the line L.
  • H-beams are usually standardized items, also known as "I-beams".
  • the core 34 defines or forms the connecting point 28, which is for example located at an extremity of the core along the line L.
  • the core 34 may include a plurality of steel H-beams mechanically connected to each other along the line L, or a grid of reinforcing steel bars at least partly surrounded by the grout 24.
  • the steel H-beam 42 and the above-mentioned variants, are adapted to withstand compression efforts, as well as traction efforts along the line L.
  • the core 34 comprises or consists of a steel chain. In that case, the core 34 is adapted to withstand only traction efforts along the line L.
  • the H-beam 42 defines a first open housing 44 and a second open housing 46 transversely opposed to each other.
  • the plates 36 are preferably orthogonal to the line L.
  • the plates 36 are rectangular.
  • three edges 48, 50, 52 of each plate 36 are welded to the web and flanges of the H-beam 42.
  • a first group 36A of the plates 36 is received in the first housing 44, and a second group 36B of the plates is received in the second housing 46.
  • the grout lines 38, 40 are adapted to deliver grout within the trench portion 20 when grout is injected under pressure in them, for example at one of their extremities along the line L.
  • the grout line 38 extends in the first housing 44, for example through holes 54 cut in the first group 36A of plates.
  • the grout line 40 extends in the second housing 46, for example through holes 56 cut in the second group 36B of plates.
  • the grout 24 for example could be a Portland grout and is adapted for curing underwater.
  • the grout 24 advantageously fills the trench portion 20 up to seabed level over at least 90% of the anchor structure 22 along the line L.
  • the grout 24 is adapted to develop a shear friction against the trench portion 20 rocky walls of as a minimum 100 kPa.
  • the mooring chain 26 is adapted to be tensioned by the floating platform 12 and to transmit/apply the efforts F to the anchor structure 22.
  • the seabed 14 is first surveyed for example by a remotely operated vehicle 60. Goal is to detect possible obstacles which could cause issues with the installation. One may also rely on previous knowledge of the seabed 14 such as bathymetry and seabed imagery.
  • the trench portion 20 is provided in the seabed 14.
  • the trench portion is dug using a subsea trencher 65 commonly used for pipeline or cables burial.
  • the remotely operated vehicle 60 and the subsea trencher 65 are equipment known in themselves and available from the market.
  • the trench portion 20 is an existing one, and does not have to be dug.
  • the trench portion 20 is cleaned, advantageously using water jets 67 ( Figure 6 ) directed at walls 69 of the trench portion.
  • the jets 67 are for example produced by the remotely operated vehicle 60.
  • the anchor structure 22 is installed, for example pre-assembled and lowered, in the trench portion 20, as shown in Figure 6 .
  • grout is injected in the trench portion 20, in the example via the grout lines 38, 40 from a source 70, in order to obtain the grout 24.
  • grouting is stopped when the trench portion 20 is full of grout, or at least when the anchor structure 22 is surrounded by grout.
  • the mooring chain 26 After curing of the grout 24, the mooring chain 26 is connected to the connecting point 28 and to the platform 12, and is tensioned. As a variant, the mooring chain 26 may have been connected to the connecting point 28 before grouting.
  • the mooring chain 26 exerts the efforts F on the anchor structure 22.
  • the above mentioned portion 30 of the mooring chain 26 lies on the seabed 14 and/or the grout 24, or the mooring chain 26 defines the angle ⁇ with a horizontal plan.
  • the anchoring process is adapted to the rocky seabed 14 and preferably catenary mooring solutions and allows reducing costs and the environmental footprint.
  • Design is fast. Limited soil investigation, for example over the top 3m of the seabed 14, is enough. All pieces of equipment are available in the market and easy to procure.
  • the final assembly of the anchor structure 22 can be done locally. Installation is fast and requires only a dynamic positioning vessel. No pretension is needed.
  • a second trench portion 120 is provided in the seabed 14.
  • the second trench portion 120 extends along a second line LL, preferably straight.
  • the second line LL and the line L converge towards the connecting point 28 and define an angle ⁇ together.
  • the second line LL and the line L also define a median axis M.
  • the angle ⁇ is advantageously comprised between 20° and 90°.
  • a second anchor structure 122 is installed in the second trench portion 120
  • the second anchor structure 122 is analogous to the anchor structure 22.
  • the second anchor structure 122 comprises a second core 134 extending along the second line LL, steel plates 136 welded to the core and extending from the second core radially with respect to the second line LL, and at least a grout line 138 extending along the second line LL.
  • the second core 134 is mechanically connected to the connecting point 28.
  • grout 124 is injected in the grout line 138 in order to fill the second trench portion 120.
  • the plates 136 are at least partly surrounded by the injected grout 124.
  • the portion 30 of the mooring chain 26 and said median axis M define a third angle ⁇ at the connecting point 28.
  • the third angle ⁇ is advantageously smaller than 30°, and preferably smaller than 10°.
  • the efforts F are split between the two halves (defined by the median axis M) of the anchoring system shown in Figure 8 .

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Ocean & Marine Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • Paleontology (AREA)
  • Civil Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Piles And Underground Anchors (AREA)
EP21306851.3A 2021-12-20 2021-12-20 Procédé d'ancrage d'une plateforme flottante sur un fond rocheux Withdrawn EP4198203A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP21306851.3A EP4198203A1 (fr) 2021-12-20 2021-12-20 Procédé d'ancrage d'une plateforme flottante sur un fond rocheux
KR1020247024401A KR20240119337A (ko) 2021-12-20 2022-12-19 암석으로 된 해저 상에 부유식 플랫폼을 정박시키는 프로세스
PCT/EP2022/086741 WO2023117966A1 (fr) 2021-12-20 2022-12-19 Processus d'ancrage d'une plate-forme flottante sur un fond marin rocheux

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP21306851.3A EP4198203A1 (fr) 2021-12-20 2021-12-20 Procédé d'ancrage d'une plateforme flottante sur un fond rocheux

Publications (1)

Publication Number Publication Date
EP4198203A1 true EP4198203A1 (fr) 2023-06-21

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Application Number Title Priority Date Filing Date
EP21306851.3A Withdrawn EP4198203A1 (fr) 2021-12-20 2021-12-20 Procédé d'ancrage d'une plateforme flottante sur un fond rocheux

Country Status (3)

Country Link
EP (1) EP4198203A1 (fr)
KR (1) KR20240119337A (fr)
WO (1) WO2023117966A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL7112844A (fr) * 1970-09-18 1972-03-21
US20140161538A1 (en) * 2012-12-12 2014-06-12 Dallas Joel Meggitt System and method for undersea micropile deployment
US10030349B2 (en) * 2010-05-28 2018-07-24 Lockheed Martin Corporation Undersea anchoring system and method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL7112844A (fr) * 1970-09-18 1972-03-21
US10030349B2 (en) * 2010-05-28 2018-07-24 Lockheed Martin Corporation Undersea anchoring system and method
US20140161538A1 (en) * 2012-12-12 2014-06-12 Dallas Joel Meggitt System and method for undersea micropile deployment

Also Published As

Publication number Publication date
KR20240119337A (ko) 2024-08-06
WO2023117966A1 (fr) 2023-06-29

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