US20230113664A1

US20230113664A1 - System and method for suction anchor deployment

Info

Publication number: US20230113664A1
Application number: US17/965,295
Authority: US
Inventors: Torleif Carlsen; Jon Tore STORESUND
Original assignee: Oceaneering International Inc
Current assignee: Oceaneering International Inc
Priority date: 2021-10-13
Filing date: 2022-10-13
Publication date: 2023-04-13
Also published as: WO2023064447A1; AU2022363657A1; EP4384440A1; EP4384440A4

Abstract

A suction anchor system comprises a substantially tubular suction anchor embeddable in a seabed, a predetermined set of sliding rails, an excavator, and a predetermined set of non-triangular wings disposed about the outer surface of the tubular, and a deployment interface which comprises a deployment cage, a suction anchor lid, and a predetermined set of deployment cage skidding rails disposed about an outer portion of the deployment cage. Using a surface vessel comprising a dispatcher which comprises a storage magazine configured to selectively receive and discharge the suction anchor, a skidding system, and an overhead anchor handler, the suction anchor can be operatively connected and secured to, and placed into fluid communication with, the deployment interface. The deployment interface along its connected suction anchor is lowed from the surface vessel into sea water using the dispatcher until the suction anchor contacts the seabed and allowed to self-penetrate below the seabed due to its own weight.

Description

RELATION TO OTHER APPLICATIONS

This application claims priority through United States Provisional Application 63/255,054 filed on Oct. 13, 2021.

BACKGROUND

The technology relates to the field of suction anchor deployment and retrieval, and specifically to deployment and retrieval of suction anchor that does not require using a remotely operated vehicle (ROV).
Suction piles (also called suction caissons or suction anchors and referred to herein as “suction anchors”) are a long steel cylinder topped with a anchor top or cap. The cap comprises valves to assist with embedment as well as connections that differ depending on the use of the suction anchor.
Suction anchors are deployed as deep mooring anchors and foundations for subsea infrastructure, applicable for “permanent” and temporary equipment. They may be used as suction anchors on large deep-water projects but are also applicable in shallow waters. Suction anchors are generally deployed from an offshore construction vessel by use of crane or from an anchor handling vessel, with or without an A-frame or other deployment aid systems. The suction anchor is lowered to a seabed and loads resisted through the structure with one or more mooring pad eyes or anchor top footings to the soil via direct bearing and skin friction. Since suction anchors are typically large steel cylinders with an open bottom, the suction anchor penetrates up to 60% of its length under its own weight, depending on soil conditions and the anchor properties. The remainder of embedment is achieved through suction: a remote-operated vehicle (ROV) pumps water out of the top suction port after sealing anchor top valves. Anchor/anchor top and ROV instrumentation contribute to a precise installation. The anchor/anchor can also be retrieved by reversing the installation process, applying an overpressure inside the caisson. Over pressurization is also applicable if boulders are in the anchor/anchor path and/ or if the vertical alignment needs adjustment.
The main problems associated with the current method of anchor deployment is the time consumption, manpower consumption and the resources e.g. (ROV) consumption. The traditional suction anchor deployment method lowers one suction anchor at a time to a seabed, then the ROV is maneuvered to the suction anchor for installing the suction anchor by operating the valves and then sealing the suction anchor after installation. So, the complete process is very time consuming, expensive and laborious.

FIGURES

Various figures are included herein which illustrate aspects of embodiments of the disclosed inventions.

FIG. 1 is a view in partial perspective of an exemplary system and FIG. 1A is a close-up view of an aft portion of that system;

FIG. 2 is a view in partial perspective of an exemplary suction anchor system;

FIG. 3 is a view in partial perspective of an exemplary deployment interface;

FIG. 4 is a view in partial perspective of an exemplary suction anchor system suspended from a vessel;

FIG. 5A and FIG. 5B are views in partial perspective of an exemplary suction anchor system deployed in water and being in contact with a seabed;

FIG. 6A and FIG. 6B are views in partial perspective of an exemplary deployment interface suspended from and being retrieved back into a vessel; and

FIG. 7A and FIG. 7B are views in partial perspective illustrating mooring lines, rods, and shear pins.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

In a first embodiment, referring generally to FIG. 1 and FIG. 1A, suction anchor system 1 comprises substantially tubular suction anchor 100 which may be embeddable in seabed 5 and deployment interface 200.
In embodiments, referring additionally to FIG. 2 , suction anchor 100 is substantially tubular and comprises tubular 101 which comprises inner annulus 102 and outer surface 103; a predetermined set of sliding rails 112 disposed about outer surface 103 of the tubular 101; internal excavator 120 disposed at least partially within tubular 101; and a predetermined set of non-triangular wings 130 disposed about the outer surface 103 of tubular 101.
Substantially tubular suction anchor 100 typically comprises a holding capacity up to around 1000 metric tons and may further comprise one or more anchor supports 113 disposed about outer surface 103 of tubular 101.
In embodiments, internal excavator 120 further comprises a predetermined set of spray nozzles 120 a disposed at least partially within inner annulus 102 of the tubular 101. The predetermined set of spray nozzles 120 a may comprise multiple spray nozzles 120 a placed inside inner annulus 102 of the tubular 101 or inside suction anchor lid 203 and spray nozzles 120 a may be capable of rotating inside suction anchor lid 203.
Further, the predetermined set of non-triangular wings 130 may further comprise a predetermined set of a set of connection points 140, e.g., padeyes 140, which may be used for connecting mooring lines 401 (FIG. 7A). Typically, the predetermined set of non-triangular wings 130 are adapted to increase anchor surface area and/or holding capacity. Where padeyes 140 are present, one or more quick lift spreader bars may be present and interfacable with one or more padeyes 140 of the predetermined set of padeyes 140. Wing design with padeyes 140 can improve onshore handling including a transfer from shore to vessel 300. Lift rigging such as lift wires or similar loose lifting gear can be replaced by a quick lift spreader bar that may also allow for multiple unit lift onto vessel 300. Padeyes 140 are typically more stable than the conventional tube-like structure and deck sea fastening can be performed quicker and safer.
In embodiments, internal excavator 120 defines a navigator, more fully described below, and deployment interface 200 typically comprises a reusable top hat/lid such as deployment cage 210 configured to support the weight of suction anchor 100; one or more load bearing connectors 220 connected to top portion 202 of deployment cage 210 and configured to operatively connect to flexible connector 331; suction anchor lid 203 disposed at least partially within deployment cage 210 and configured to selectively interface with tubular 101; and a predetermined set of deployment cage skidding rails 280 disposed about an outer portion of deployment cage 210 where the predetermined set of skidding system rails 321 is further configured to slidingly accept the predetermined set of deployment cage skidding rails 280. The predetermined set of skidding rails 280 may comprise a predetermined set of modular skidding rails 280.
Typically, deployment cage 210, which may be sufficiently open to allow fluid flow through top portion 202 of deployment cage 210, comprises steel or similar material capable of holding the weight of suction anchor 100 and is welded or integral. In embodiments, deployment cage 210 may be reusable and comprise reusable suction anchor lid 203 such as to allow installation of each different suction anchor, e.g., that releasably attaches to detachable suction anchor 100.
In embodiments, the navigator is disposed at least partially within deployment cage 210. Deployment interface 200 may further comprise one or more power supplies 270 disposed at least partially within deployment cage 210 and operatively connected to the navigator and one or more deployment interface locks 290 disposed about an outer portion of deployment cage 210 and configured to operatively connect suction anchor 100 to deployment interface 200. Additionally, the navigator may comprise a predetermined set of thrusters 250.
In embodiments, the navigator further comprises one or more pumps 230, which may be vacuum pumps or venturi ejectors or the like, disposed at least partially within deployment cage 210 and operatively connected to power supply 270, and one or more valves 240, which may be butterfly valves, in fluid communication with pump 230 and disposed at least partially within deployment cage 210. The use of a venturi ejector instead of a conventional suction anchor pump, e.g., a centrifugal or impeller-based pump, may provide a degree of robustness as debris can go through an open pump section and small debris or rocks will not affect pump 230. A venturi ejector pump 230 may also relieve the need for valves to bleed the trapped air because a venturi system is of an open design during the decent through the water column. As opposed to ROV performed alignment of a heading of suction anchor 100 along with whatever needs to be restrained, the disclosed system can use the exhaust of pump 230, combined with a remotely controlled valve system, to rotate/align heading. Auto alignment may also be software controlled, to automize the complete installation process or part thereof.
Pump 230 is typically in fluid communication with, and adapted to create negative pressure inside, inner annulus 102 of tubular 101. If pump 230 comprises a venturi ejector the venturi ejector is typically configured to route debris through an open pump section and small debris or rocks will not affect the pump. Typically, the venturi ejector comprises a venturi ejector pump which obviates a need for a valve to bleed trapped air and an open design during a decent through a water column, where exhaust of venturi ejector pump 230, combined with remotely controlled valve system, can rotate and align a heading of suction anchor 100.
Valve 240 may be used to vent off air during splash zone passing and may not be a butterfly valve if a venturi ejector is used.
Direct power source connection 272 may be present, connected to pump 230, and configured to interface with a power conductor in umbilical 340.
In embodiments, a predetermined set of sensors 260 are present, where sensor 260 may comprise an inclinometer, a depth sensor, a current sensor, a gyroscope, a multibeam transponder, or the like, or a combination thereof. In these embodiments, data communicator 262 may be present and operatively in communication with sensors 260.
Referring back to FIG. 1 , system 2 allows for deployment of suction anchor system 1 and does not require a remotely operated vehicle ROV to deploy suction anchors 100. System 2 comprises an embodiment of suction anchor system 1, which is as described above, and surface vessel 300, which comprises vessel deck 301 and dispatcher 330 disposed proximate vessel deck 301.
Suction anchor 100 is a headless suction anchor 100, i.e., it is open at both ends, and typically shorter than the existing solutions, allowing for adding multiple suction anchors 100 to be disposed on vessel deck 301. The reduced length indirectly also reduces weight, welding and painting. The overall design complexity of the subsea installed suction anchor 100 is reduced further when considering all the functionality that now is transferred to a reusable top section, i.e., deployment interface 200, and its associated valves, vent hatches, grabber bar, temporary sensors, and the like.
In embodiments, referring back to FIG. 1A, dispatcher 330 comprises one or more storage magazines 310 configured to selectively receive one or more suction anchors 100; skidding system 320, comprising a predetermined set of skidding system rails 321 configured to slidingly accept the predetermined set of sliding rails 112; and overhead anchor handler 331.
In embodiments, overhead anchor handler 331 comprises winch 332 and one or more flexible connectors 333 operatively in communication with winch 332.
Deployment interface 200 and suction anchor 1 are typically detachably connected to each other on vessel deck 301 and deployable as a single unit to seabed 5.
Power supply 270 is also as described above and may further comprise one or more primary power sources; one or more direct power sources; one or more secondary power sources, which typically comprises one or more batteries which may be operatively connected to pump 230; and one or more valves 240. In addition, power supply 270 may comprise an umbilical interface which further comprises a power source interface.
System 2 may further comprise one or more remote operation controllers which can allow control of system 2 from the vessel or remotely, via 4G, satellite etc., to allow for reduced on board personnel.
In the operation of exemplary methods, referring back to FIG. 1 and generally to FIGS. 5A-8 , suction anchor 100 may be deployed using system 2 without using a remotely operated vehicle ROV, typically by operatively connecting and securing suction anchor 100 to deployment interface 200 such as via locking mechanism, e.g., deployment interface lock, which can that can comprise one or more water powered linear actuators such as cylinders or other similar means. The connection of suction anchor 100 to deployment interface 200 can allow suction anchor lid 203 to be in a fluid communication to allow transfer of fluids with suction anchor head 104.
Typically, suction anchor 100 is connected to deployment interface 200; flexible connector 331, e.g., a wire or cable, is connected to load bearing connector 220 of deployment interface 200 which is lowered along its connected suction anchor 100 from surface vessel 300 into sea water using dispatcher 300 until suction anchor 100 contacts seabed 5. Once in contact, suction anchor 100 is allowed to self-penetrate below seabed 5 due to its own weight. Typically, suction anchor 100 is completely embedded in seabed 5 more deeply than with conventional suction anchor installation processes because the top of suction anchor 100 is open. Thus, no support from vessel 300 or an ROV is required to install suction anchor 100. It is noted that a lidless, or open, suction anchor 100 will typically be shorter than the existing solutions, allowing for adding multiple suction anchor anchors 100 on deck 301 of vessel 300. The reduced length indirectly also reduces weight, welding, and painting. The overall design complexity of the subsea installed unit is reduced further when considering all the functionality that now is transferred to a reusable top section, i.e., deployment interface 200.
Generally, suction anchors 100 are transported to a deployment site by vessel 300 or an anchor handling type vessel or barge and deployed to seabed 5 using deployment interface 200 which is typically capable of being detachably connected to suction anchor 100.
Lowering the deployment interface may further comprise lowering the suction anchor 100 at an initial height of up to 4 m above seabed 5 and further lowering suction anchor 100 in a predetermined mode, e.g., a constant tension mode.
In embodiments, after allowing suction anchor 100 to self-penetrate into, and possibly below, seabed 5 due to its own weight, suction anchor 100 is lowered further into seabed 5 and a few tons of constant tension maintained to ensure that suction anchor 100 is aligned substantially vertical. In these embodiments, after allowing suction anchor 100 to self-penetrate below seabed 5 due to its own weight, pump 230 may be switched on to create negative pressure inside suction anchor 100 and used to pump out water and soil or water-soil mixture in order to fix suction anchor 100 deeper into seabed 5.
Where multiple spray nozzles 120 a are present as described above, and spray nozzles 120 a are capable of rotating inside the suction anchor lid, multiple spray nozzles 120 a may be used to aid deployment of suction anchor 100 into seabed 5 by using spray nozzles 120 a to perform a jetting operation which clears the path using jets of high pressure to create a guided bore for embedding suction anchor 100 into the sea bed.
Where pump 230 comprises a venturi ejector, suction anchor 100 may be rotated by using venturi offset exhaust pressure by moving and angling the venturi offset exhaust relative to deployment interface 200. The suction aids in self-penetration of suction anchor 100 into seabed 5, e.g., pump 230 is switched on to create negative pressure inside suction anchor 100 and pump out water and soil or water-soil mixture in order to fix suction anchor 100 deeper into seabed 5.
In embodiments, deployment interface 200 may be recovered back to deck 301 of vessel 300 and a next suction anchor 100 moved along skids 320 to a predetermined position where it can be connected to deployment interface 200 for deployment. In certain embodiments, soil may be dredged and removed above suction anchor 100 to connect deployment interface 200 to suction anchor head 104; deployment interface 200 reconnected to suction anchor 100; and once connected, pumping restarted to remove suction anchor 100 from seabed 5.
In certain embodiments, system 2 can also facilitate simultaneous deployment of suction anchors 100 and multiple deployment interfaces 200 can work in parallel.
In all of these embodiments, system 2 may be remotely operated using wireless technologies such as buoy, acoustics, and seawater optics.
Referring now to FIG. 7A and FIG. 7B, mooring line 401 is hooked up to one or more mooring latching rods 402 present on suction anchor 100. Each mooring latching rod 402 may be fastened with or to non-triangular wings 130 such as by using a pivoting connection. Further a shear pin 403 may be provided to temporarily restrict movement until the mooring line is connected to the mooring latching rod 402. The stability and design of the mooring latching rod 402 allows quick connection of the mooring line connector. Mooring line 401 may comprise a chain mooring line, a wire mooring line, a synthetic fiber rope, or the like, or a combination thereof. Each mooring line 401 is pulled in once attached with a floating body which breaks shear pin 403 due to load and sets on a correct configuration. Further, if suction anchor 100 is not required to be removed from seabed 5, the mooring lines 401 may be disconnected and suction anchor 100 left embedded into or under seabed 5.
The foregoing disclosure and description of the inventions are illustrative and explanatory. Various changes in the size, shape, and materials, as well as in the details of the illustrative construction and/or an illustrative method may be made without departing from the spirit of the invention.

Claims

1. A suction anchor system, comprising:

a) a substantially tubular suction anchor embeddable in a seabed, comprising:

i) a tubular comprising an inner annulus and an outer surface;

ii) a predetermined set of sliding rails disposed about the outer surface of the tubular;

iii) an excavator disposed at least partially within the tubular; and

iv) a predetermined set of non-triangular wings disposed about the outer surface of the tubular; and

b) a deployment interface, comprising:

i) a deployment cage configured to support the weight of the suction anchor;

ii) a load bearing connector connected to a top portion of the deployment cage and configured to operatively connect to the flexible connector;

iii) a suction anchor lid disposed at least partially within the deployment cage and configured to selectively interface with the tubular; and

iv) a predetermined set of deployment cage skidding rails disposed about an outer portion of the deployment cage, the predetermined set of skidding system rails further configured to slidingly accept the predetermined set of deployment cage skidding rails.

2. The suction anchor system of claim 1, wherein the predetermined set of non-triangular wings further comprises a predetermined set of padeyes.

3. The suction anchor system of claim 1, wherein the deployment interface further comprises a deployment interface lock disposed about an outer portion of the deployment cage and configured to operatively connect the suction anchor to the deployment interface.

4. The suction anchor system of claim 1, wherein the internal excavator further defines a navigator disposed at least partially within the deployment cage, comprising:

a) a predetermined set of spray nozzles disposed at least partially within the inner annulus of the tubular;

b) a power supply disposed at least partially within the deployment cage;

c) a pump disposed at least partially within the deployment cage and operatively connected to the power supply;

d) a valve in fluid communication with the pump and disposed at least partially within the deployment cage;

e) a predetermined set of thrusters; and

f) a predetermined set of sensors.

5. The system for deployment of a suction anchor of claim 4, wherein the sensors comprise an inclinometer, a depth sensor, a current sensor, a gyroscope, a multibeam transponder, or a combination thereof.

6. The suction anchor system of claim 4, further comprising a direct power source connection connected to the pump and configured to interface with a power conductor in an umbilical.

7. The suction anchor system of claim 4, wherein the pump is in fluid communication with, and adapted to create negative pressure inside, the inner annulus of the suction anchor.

8. A system for deployment of a suction anchor system without requiring a remotely operated vehicle (ROV), comprising:

a) a suction anchor system, comprising:

i) a substantially tubular suction anchor embeddable in a seabed, comprising:

(1) a tubular comprising an inner annulus and an outer surface;

(2) a predetermined set of sliding rails disposed about the outer surface of the tubular;

(3) an excavator disposed at least partially within the tubular; and

(4) a predetermined set of non-triangular wings disposed about the outer surface of the tubular; and

ii) a deployment interface, comprising:

(1) a deployment cage configured to support the weight of the suction anchor;

(2) a load bearing connector connected to a top portion of the deployment cage and configured to operatively connect to the flexible connector;

(3) a suction anchor lid disposed at least partially within the deployment cage and configured to selectively interface with the tubular; and

(4) a predetermined set of deployment cage skidding rails disposed about an outer portion of the deployment cage, the predetermined set of skidding system rails further configured to slidingly accept the predetermined set of deployment cage skidding rails; and

b) a surface vessel, comprising:

i) a vessel deck; and

ii) a dispatcher disposed proximate the vessel deck, comprising

(1) a storage magazine configured to selectively receive and discharge the suction anchor;

(2) a skidding system comprising a predetermined set of skidding system rails configured to slidingly accept the predetermined set of sliding rails and the predetermined set of deployment cage skidding rails; and

(3) an overhead anchor handler system, comprising:

(a) a winch; and

(b) a flexible connector operatively in communication with the winch, the flexible connector further operatively, selectively connected to the load bearing connector.

9. The system for deployment of a suction anchor of claim 8, wherein the predetermined set of skidding rails comprises a predetermined set of modular skidding rails.

10. The system for deployment of a suction anchor of claim 8, where the storage magazine is configured to carry multiple suction anchors.

11. The system for deployment of a suction anchor of claim 8, wherein the deployment interface and suction anchor are configured to be connected to each other on the vessel deck of the surface vessel and deployable as a single unit to seabed 5.

12. The system for deployment of a suction anchor of claim 8, wherein the suction anchor lid comprises a reusable suction anchor lid configured to be reusably connected to a plurality of suction anchors, one at a time, to allow installation of each different suction anchor.

13. A method of deployment of a suction anchor without using a remotely operated vehicle (ROV), using a system comprising a suction anchor system, comprising a substantially tubular suction anchor embeddable in a seabed, which comprises a tubular comprising an inner annulus and an outer surface, a predetermined set of sliding rails disposed about the outer surface of the tubular, an excavator disposed at least partially within the tubular, and a predetermined set of non-triangular wings disposed about the outer surface of the tubular; a deployment interface which comprises a deployment cage configured to support the weight of the suction anchor, a load bearing connector connected to a top portion of the deployment cage and configured to operatively connect to the flexible connector, a suction anchor lid disposed at least partially within the deployment cage and configured to selectively interface with the tubular, and a predetermined set of deployment cage skidding rails disposed about an outer portion of the deployment cage, the predetermined set of skidding system rails further configured to slidingly accept the predetermined set of deployment cage skidding rails; and a surface vessel comprising a vessel deck and a dispatcher disposed proximate the vessel deck which comprises a storage magazine configured to selectively receive and discharge the suction anchor, a skidding system comprising a predetermined set of skidding system rails configured to slidingly accept the predetermined set of sliding rails and the predetermined set of deployment cage skidding rails, and an overhead anchor handler system which comprises a winch and a flexible connector operatively in communication with the winch, the flexible connector further operatively, selectively connected to the load bearing connector, the method comprising:

a) operatively connecting and securing the suction anchor to the deployment interface;

b) placing the suction anchor into fluid communication with the deployment interface;

c) connecting the flexible connector to the load bearing connector of the deployment interface;

d) lowering the deployment interface along its connected suction anchor from the surface vessel into sea water using the dispatcher until the suction anchor contacts a seabed; and

e) allowing the suction anchor to self-penetrate below the seabed due to its own weight.

14. The method of claim 13, wherein lowering the deployment interface further comprises:

a) lowering the suction anchor at an initial height of up to 4 m above the seabed; and

b) further lowering the suction anchor in constant tension mode.

15. The method of claim 13, further comprising, after allowing the suction anchor to self-penetrate below a seabed due to its own weight:

a) lowering the suction anchor further into the seabed; and

b) maintaining a few tons of constant tension to ensure the suction anchor is vertical.

16. The method of claim 15, further comprising, after allowing the suction anchor to self-penetrate below the seabed due to its own weight:

a) switching on the pump to create negative pressure inside the suction anchor; and

b) using the pump to pump out water and soil or water-soil mixture in order to fix the suction anchor deeper into the seabed.

17. The method of claim 16, wherein the suction anchor lid further comprises multiple spray nozzles placed inside the suction anchor lid, the spray nozzles capable of rotating inside the suction anchor lid, the method further comprising using the multiple spray nozzles to aid deployment of the suction anchor into the seabed by using the spray nozzles perform jetting operation which clears the path using jets of high pressure to create a guided bore for embedding suction anchor.

18. The method of claim 16, further comprising:

a) unlocking the locking mechanism to detach the deployment interface from the suction anchor system, thereby removing the fluidic connection between the suction anchor lid and the suction anchor head; and

b) recovering the deployment interface to the deck of the surface vessel.

19. The method of claim 18, further comprising:

a) moving a next suction anchor along the skids to a predetermined position; and

b) connecting the next suction anchor to the deployment interface for deployment of the next suction anchor.

20. The method of claim 16, further comprising:

a) dredging to remove soil above the suction anchor to connect the deployment interface to the head of the suction anchor;

b) reconnecting the deployment interface to the suction anchor; and

c) once connected, pumping to remove the suction anchor from the seabed.