EP2683876B1

EP2683876B1 - System and method for installation of off shore foundations

Info

Publication number: EP2683876B1
Application number: EP12710199.6A
Authority: EP
Inventors: Damian CALLAN; John McCAREY; Adam HOLLAND; Adrian Quinn
Original assignee: Mclaughlin & Harvey Ltd; Rps Group PLC
Current assignee: Mclaughlin & Harvey Ltd; RPS GROUP PLC
Priority date: 2011-03-11
Filing date: 2012-03-12
Publication date: 2017-03-01
Anticipated expiration: 2032-03-12
Also published as: GB201104183D0; WO2012123431A1; EP2683876A1; GB2488839B; CA2829739C; GB2488839A; CA2829739A1

Description

The present invention relates to a system and a method for providing foundations for underwater (subsea) structures using one or more tension anchors to fix the structure to the seabed. Such underwater foundations are required for fixing and supporting apparatus onto the bed of the sea, river or estuary and are generally disclosed in US 7 380 614 B1 . Such apparatus positioned on the bed of the sea, river or estuary may comprise energy conversion systems including, but not limited to, tidal stream turbines.
Reference to the term "seabed" throughout this description is to be understood to include any underwater floor bed.
In particular, the present invention relates to methods for the installation of subsea foundations to the seabed to which a wide variety of subsea apparatus can be attached and most particularly, the present invention provides post tensioned anchored foundations installed using submergible robotic equipment.
The system and method of the present invention can be used with any type of underwater bed anchorage. However, the present invention will be described and discussed herein with reference to its main application which is providing foundations for water current energy conversion systems, such as tidal energy conversion systems and wave energy conversation systems.

BACKGROUND TO THE INVENTION

With the continued development and commercialisation of devices designed to recover energy from marine environments such as tidal stream turbines and wave energy conversion devices, there is an urgent requirement for the development of new techniques and equipment to facilitate the quick, safe and cost effective installation of devices and their foundations on the seabed. This presents particular technical problems in the marine environments where these devices are to be installed especially in the areas of strong tidal motion where devices such as tidal stream turbines are installed.
The installation techniques that have, until now, been used to install the current single larger scale demonstrator devices fall into two main groups, namely, oil and gas technology; and marine civil engineering technology. While there is undoubtedly equipment that can and has been used from the oil and gas industry, the costs involved are prohibitive for commercial deployment, given commercial return from the energy output over the life time of the installation.
In the prior art, when installing subsea structures for the Oil and Gas and Renewable Energy industries, typically, underwater piled foundations are used and these are installed by equipment operated from surface vessels. Alternatively, heavily ballasted structures are used. This requires specialised vessels for long periods of time which is prohibitively expensive.
The pile locations have to be accurate to allow prefabricated foundation units to be installed. This accuracy has to be achieved tens of metres below the sea surface.
In locations of significant overburden or where the bedrock is weak or fractured, the pile length and diameter has to be increased, requiring deeper and wider holes to be drilled into the seabed, and consequentially longer and larger diameter piles.
Marine civil engineering equipment has been used but this equipment is more suited for the sheltered coastal environment for which it has been designed. The challenging environmental conditions prevalent at the locations of the more energetic marine energy sites have for the most part been avoided, up to now, because of the difficulty and high cost involved in installing and maintaining infrastructure on these sites. Furthermore, obtaining good accurate site investigation information from these prospective sites is both difficult and costly.
The present invention seeks to overcome the disadvantages of the prior art.
It is a purpose of the present invention to provide a system for installing a foundation for a subsea structure as detailed in claim 1. Also provided is a method for installing foundations in the seabed according to claim 13. Advantageous features are provided in the dependent claims. The present invention accordingly provides a system for installing a foundation for a subsea structure, the system for installing a foundation for subsea structures comprising at least one tension anchor and means for embedding said at least one tension anchor into the seabed.
The system for installing a foundation to a subsea structure preferably comprises a foundation frame which is provided with anchoring means, the foundation frame being adapted to support and be removably connected with apparatus such as energy conversion apparatus and the anchoring means, in use, being embedded in the seabed. Preferably, the system comprises control means wherein the control is carried out remotely from the installation, the control means being connected to the installation.
Advantageously, this system for the installation of a subsea foundation comprises an installation and drilling frame carrying drilling means; the installation and drilling frame being removably connectable to the foundation frame.
The present invention provides a system and a method for the installation of a subsea foundation including at least one tension anchor in the seabed and a foundation frame to which a wide variety of structures/apparatus can be attached.
Thus, the foundation frame may be a single tension anchored foundation frame or multiple tension anchored foundation frame for providing a foundation to subsea structures which in use, are mounted onto the foundation frame which in turn is anchored into the seabed by the single or multiple tension anchors provided on the foundation frame.
To achieve the accurate positioning of the tension anchors, the prefabricated foundation frame structure itself is used as the locating template for the drilling equipment.
The tension anchor preferably comprises a hollow self-drilling anchor or a tubular anchor, preferably incorporating a detachable drill bit. Advantageously, the hollow anchor also includes a drive means, optionally comprising a drive shoe.
Furthermore in accordance with the system of the present invention, the tension anchor(s) is/are installed using robotic underwater installation equipment connected to a support vessel by umbilical cables.
Furthermore, the type, diameter and/or length of the anchor bar, the anchoring material and the bond length into the seabed can be adjusted to suit a wide variety of seabed conditions.
Furthermore, an advantage of the system and method of the present invention is that the integrity of the anchor can be tested, proof loaded and post tensioned with loads greater than the maximum design load so that the anchor(s) always remain in tension during its/their service life, thus reducing the cyclic loading on the anchor and reducing the need for costly onsite investigation or the consequences of failures during the service life.
Features of the system, apparatus and method for installing a subsea foundation in accordance with the present invention are set out in the appended Claims.
Throughout this specification, reference is made to the preferred embodiment involving use of grout as a solidifying anchoring material to secure the anchor in the seabed and the preferred embodiment was grout, pre-installed in grout bags. However, it is to be understood that any material which changes from a fluid form to a solid form so as to provide an anchoring material can be used for this function. References to "grout" are to be interpreted and understood accordingly.
Furthermore, although the preferred means of pre-installing the solidifying anchoring material which solidifies around the anchor bar is in grout bags, the invention is not limited to this means of pre-installation of the solidifying material.
The present invention will now be described more particularly, by way of example only, with reference to the accompanying drawings, in which are shown a number of alternative embodiments of the system of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

Figure 1 illustrates the lowering of the installation and drilling frame and system for installation of a foundation frame from under a barge 38 to the seabed;
Figure 2 illustrates the installation and drilling frame and system for installation of foundations on the seabed and the recovery of the lifting frame while the system for installation of foundations remains connected by umbilical cables 50 to a command and control vessel 37;
Figure 3 illustrates the foundation frame, installation and drilling frame and the lifting frame on the deck of a deployment vessel; this is not the preferred deployment method but is shown as an alternative methodology to the preferred embodiment shown in the other figures and discussed herein below;
Figure 4 illustrates the lowering of the foundation frame, installation and drilling frame and lifting frame to the seabed;
Figure 5 is a sectional view of the system of the invention for installing a single tension anchor foundation into the seabed and showing the foundation frame; and installation and drilling frame being levelled on the seabed;
Figures 6, 7 and 8 are a sectional view of the system of the invention for installing a single tension anchor foundation and illustrate the drilling of the tension anchor into the seabed and illustrating the grouting and the application of pre loading/proof loading to the tension anchor to check the integrity of the installation of the foundation frame and increase the penetration of the tension anchor into the seabed;
Figure 9 is an enlarged view showing the conductor shoe and grout bags;
Figure 10 is an enlarged view of the anchor head;
Figures 11, 12 and 13 are sectional views showing the system of the invention for installing the single tension anchor foundation configured to incorporate a down the hole hammer and detachable drill head for installation of a hollow tubular anchor;
Figure 14 shows a sectional view of the drill carriage on which the drill drifter or rotary drive head will be mounted, and the ram and pulley arrangements that will be used to move the drill carriage up and down the drill mast;
Figures 15, 16, 17, 18, 19 and 20 show the sequence of operations for installation of a foundation frame provided with three tension anchors, on the sea bed using an under-slinging barge incorporating lifting equipment;
Figures 21, 22, 23, 24, 25, 26, 27 and 28 show the sequence of operations for installing an electrical connection plate, J-tube and a length of sub-sea export cable on to the foundation frame using an alignment and installation frame and cable installation vessel;
Figures 29, 30, 31, 32, 33, 34, 35, and 36 show the installation of a nacelle using an alignment and installation frame;
Figures 37, 38, 39, 40, 41, 42, 43, 44 and 45 show the installation of a nacelle and J-tube subsea cabling carried out in a single operation;
Figure 46 is a perspective view of one embodiment of the invention for the installation of a three anchor foundation, showing the foundation frame and including the installation and drilling frame land ifting frame with alignment members;
Figures 47, and 48 are sectional views of the means provided for adjusting the length of the foundation legs showing so that the foundation frame can be levelled and also so that the foundation legs can be installed and tested and pre-loaded independently while ensuring that jacking loads are not transferred into the foundation frame.
Figures 49, 50, 51 and 52 show the sequence of operations for using the levelling legs of the installation and drilling frame to level the foundation frame during drilling and ensuring that the foundation frame remains level after anchor installation in the sea bed.

DETAILED DESCRIPTION OF THE DRAWINGS

In the drawings, the following reference numerals are used to indicate the correspondingly indicated features:

1. Levelling Jack Base Plate
2. Levelling Jack and Accumulator
3. Anchor Stop block
4. Chuck
5. Rotary Drifter Head
6. Manifold/Valve Block
7. Hydraulic flow/return and bleed lines
8. Grout Lines
9. Grout Flushing Line
10. Side Entry Swivel
11. Drill Rig Support Housing
12. Water Pump
13. Drill String/Hollow Anchor
14. Mechanical Clamp/Connection
15. Alignment Guide
16. Foundation frame
17. Grout/Manifold/Valve Block
18. Decommissioning duct for explosive charge
19. Bearing Plate
20. Grout Bags
21. Conductor Shoe
22. Drill String/Anchor Head
23. Conductor
24. Penetrating Shoe
25. Seal
26. Arisings Exhaust Duct
27. Bleed valve
28. Jacking Chamber
29. Stressing Stool
30. Subsea Structure/Apparatus
31. Shear Key
32. End Stop
33. Aligning guide
34. Adjustable Levelling Leg
35. Foundation leg shear key
36. Grouted Connection
37. Command and Control Vessel
38. Deployment Barge
39. Tug Boat
40. Installation and Drilling Frame
41. Foundation Frame
42. Lifting Frame
43. Nacelle/Cable Deployment and/or retrieval frame
44. Bend Restrictors
45. Sub Sea Export Cable
46. Nacelle
47. Cable Drum
48. Cable Engine
49. Shute
50. Umbilical
51. Cable Installation Vessel
52. Top Drive Rotary Head
53. Down the Hole Hammer
54. Detachable Drill Head
55. Tubular anchor/casing
56. Casing Drive Shoe
57. Drill Carriage
58. Drill Carriage wire rope
59. Drill Carriage Sheave
60. Drill Carriage Ram
61. Electrical Connection Plate (wet mate)
62. J Tube with articulated joint
63. Mechanical Coupling Means
64. Alignment Guide members

Referring initially to Figures 1 and 2, in this preferred embodiment, the foundation frame, the installation and drilling frame and lifting frame are pre assembled and brought to site preferably winched underneath the deployment vessel 38, a floating platform or barge. An additional command and control vessel 37 will remain connected to the installation and drilling frame by various cables, hoses and load wires to provide power to operate the drills, hydraulic systems etc. to supply and deliver the grouts for the operations and to send command and receive feedback signals for the operation of the installation and drilling frame.
An alternative but less preferred option, as shown in Figures 3 and 4, the foundation frame, installation and drilling frame and lifting frame are assembled on the deck of a deployment vessel 38, which may be a heavy lift barge or a DP vessel with sufficient deck and crane capacity to lift and lower the foundation frame, the installation and drilling frame and the lifting frame from the vessel deck to the seabed. In the case of the DP vessel, the foundation frame could be firstly lowered onto the seabed, then installation and drilling frame could be lowered and mechanically connected to the foundation frame so that the capacity of its deck crane could be reduced. The DP vessel could also be connected to the installation and drilling frame and provide the functions of the second command, control and power supply vessel.
As shown in Figures 5 and 46, the assembled installation and drilling frame and foundation frame have now been lowered onto the seabed preferably by a three point lifting arrangement. The installation and drilling frame is designed so that the three landing/levelling jacks contact the seabed before the central drill string 13. The installation and drilling frame incorporates levelling means (see Figures 47 to 52; such that the installation and drilling frame can be adjusted to level by remotely operating the hydraulic jacks built into the installation and drilling frame. The command signals are sent from the command vessel. Sensors on the drill frame will indicate when the foundation frame is within tolerance. Any number of drill strings can be installed per foundation frame. The drill string(s) and foundation frame can be installed at the same time, as for example, the arrangement shown in Figure 11 which shows a foundation frame with three drill strings. Shock absorption can be incorporated into the landing/levelling legs by installing hydraulic accumulators and valves into the hydraulic circuit thereby reducing shock loads and the requirement for heave compensation on the lowering equipment.
Using data supplied to the command vessel from sensors installed on the installation and drilling frame and the foundation frame, the position, level and alignment of the foundation frame can be verified.
If the position of the installation and drilling frame/foundation frame is within tolerance i.e. there is sufficient travel in the jack legs 2 to bring the foundation frame into level, the lifting frame is disconnected from the installation and drilling frame/foundation frame and the lifting frame is recovered to the deployment vessel.
In any case the deployment of the installation and jacking frame and foundation frame to the sea bed, the disconnection of the lifting frame and it recovery to the installation vessel must be carried out during one single tidal cycle i.e. during either a flood or ebb cycle. If for any reason the deployment to the sea bed cannot be completed in the time allotted the operation will be aborted and if required remobilised for the next tidal window.
An alternative but less preferred option would be to use two tugs one upstream and one downstream, to position the deployment barge, this option would make the marine operations more complicated but would extend the window for deployment of the equipment onto the seabed to more than one tidal cycle.
In any iteration where more than a single foundation frame/drill string is being installed, a system is incorporated into the foundation frame legs so that the length of each leg can be adjusted so as to compensate for unevenness or sloping gradient in the seabed as shown in Figures 47 to 52.
The deployment vessel can now depart the deployment site and return to port or stand by until it is required later in the operations.
The installation and drilling frame and consequently the foundation frame to which it is connected can now be levelled and if required, lowered until the foundation leg bearing plate 19 touches the seabed by adjusting the hydraulic pressures in the three rams built into the installation and drilling frame. Hydraulic oil pressure/flow can be supplied from either, hydraulic power packs and valves built into the installation and drilling frame or through umbilical/cables from hydraulic power packs on the command and control vessel to the installation and drilling frame. The alignment and level of the foundation frame can also be determined from signals sent from sensors on the installation and drilling frame to instruments on the command vessel to confirm that it is within the required specification.
Referring now to Figures 5 to 10 a drill string comprising a hydraulic rotary drifter head 5, chuck, side entry swivel 10 for introducing flushing fluid and grout to the anchor, stop block 3 on the anchor to transfer the jacking loads from the anchor bar 13 to the stressing stool 29, a hollow centre anchor bar 13, a drill bit 22, hydraulic clamps to grip the anchor and a system to raise and lower the drill string is pre-installed on the installation and drilling frame as shown in Figure 14. The hydraulic or pneumatic lines 7, grout lines 8 and flushing line 9 required to operate the drill system can be marshalled inside the outer casing using retractable cables as shown in Figure 6. Using the rotary percussive drifter head 5, the drill bit 22 forms a hole in the seabed and concurrently drives the conductor shoe 21 into the seabed until the conductor shoe reaches its end stop 32. Shear keys 31 in the conductor shoe 21 then break off or deform allowing the drill bit and anchor to continue forming the anchor hole. As the anchor is drilled into the seabed, the drill arisings are flushed out of the drilled hole along the drill conductor and exit through the exhaust duct 26 into the water column. The flushing medium, preferably sea water, is supplied from a water pump 12 mounted on the installation and drilling frame but alternatively water, weak grout mix, drilling mud or air from the command and control vessel could also be supplied for the same function. Drilling continues until the stop block 3 on the anchor bar contacts the stressing stool top plate 29.
Preferably, a cementatious grout is introduced into the central channel in the anchor bar from the command vessel through a grout line.
Furthermore, although the preferred means of pre-installing the solidifying anchoring material which solidifies around the anchor bar is in grout bags, the invention is not limited to this means of pre-installation of the solidifying material.
Alternatively, instead of using cementations grout, a chemical anchoring material which solidifies may be used. Thus, for instance, in the embodiment using a chemical anchoring material, the chemical anchor dosing, mixing, installation equipment with the associated power packs, pipe work and valves is installed on the installation and drilling frame instead of grout pre-installed in grout bags.
Throughout this specification, reference is made to the preferred embodiment involving use of grout pre-installed in grout bags. However, it is to be understood that any material which changes from a fluid form to a solid form so as to provide an anchoring material can be used.
The quantity and supply pressure of the grout injected during installation can be monitored and the values used to determine that the anchor bar has been fully grouted. De-bonding material can be pre-installed over a set length of the upper section of the anchor bar so that when the anchor bar is pre-loaded, the de-bonded length is free to stretch.
Alternatively in locations where there is significant overburden or where the characteristics of the sea bed or foundation design, preclude the use of a self-drilling anchor, down the hole drilling techniques can be used to install a hollow tubular anchor.
Referring now to Figures 11, 12 and 13, the drill string now comprises a top drive rotary head (52), a chuck (4), a side entry swivel (10) a drill string (13) a "down the hole" hammer (DTH) (53), a tubular casing/anchor (55) incorporating a casing drive shoe (56) and a consumable detachable drill bit (54).
As before, the drill is started and the drill hole progressed. Rotary motion and vertical pressure is applied through the rotary motion head from the drill carriage. The flushing medium is supplied through the side swivel and hollow drill string to the drill bit. Arises are flushed out of the drilled hole and through exhaust duct 26.
As before, drilling proceeds until end stop 3 contacts the top of the stressing stool 29. Grouting can now take place around the annulus of the anchor as before. On completion of this grouting process, the drill bit is disconnected and the drill string and DTH retracted. Further grout can be placed as the DTH is retracted, to fill the centre of the drill string if required. At this stage the grout lines and DTH can be flushed out. A non-return/check valve is incorporated into the drill bit to maintain the head of grout around the anchor bar. On completion of this grouting operation, the DTH can be retracted and locked in the fully raised position.
Now referring to Figure 9, following curing, a fluid preferably water is introduced through grout manifold/valve block 17 into jacking chamber 28. Valve 27 is opened to bleed off any trapped air. When all air has been expelled, valve 27 is closed and the pressure in jacking chamber 28 is increased to a predetermined value. This will have the effect of moving the stressing stool to react against stop block 3 on the anchor bar and so transfer the load through the anchor bar into the point of fixity within the seabed. This will have the further effect of forcing the foundation frame penetrating shoe 24 further into the seabed. The force applied can be controlled by adjusting the fluid pressure in chamber 28. This pressure can be further adjusted to set values and timings to load and unload the anchor as required proving the installation.
The bearing plates 19 determine the maximum amount of penetration of the foundation frame into the seabed. When testing of the anchor is complete, marker dye followed by a grout will be introduced into the jacking chamber 28. Valve 27 is partially opened so that a pre-determined pressure remains in the circuit. When the marker dye flows out of valve 27, the valve is fully closed and the grout pressure increased so that a force equal to the projected maximum design load, with an additional appropriate allowance factor, of safety is now applied to the anchor. Inlet valve 17 is closed and the pressure monitored.
Now grout bags 20 preinstalled in the bottom of the foundation frame can be inflated by pumping grout through grout manifold 17 and so fill any voids between the bottom of the foundation frame and the seabed. This grout when cured will further resist any penetration of the foundation frame leg into the seabed, provide scour (erosion) protection at the base of the foundation frame and resist the shear loads imposed on the structure.
In any iteration where more than a single foundation frame/drill string is to be installed, adjustment of the foundation legs is provided. The procedure is described as follows.
Referring to Figures 47, and 48 the inner foundation leg 34 is held in the raised position by drill string 13, this is in turn held by the drill chuck and carriage. The foundation frame is placed on the seabed and the foundation levelled as before. Referring to figure 49 and 50 it can be seen that these inner foundation legs are held clear of the sea bed after the levelling of the installation and drilling frame.
The drill carriages are operated and the inner foundation frame leg is free to move through the foundation frame 41, guides 33 keep the inner leg central with the foundation frame.
Following drilling, grouting, testing and pre tensioning of the anchors grouting of the annulus of the inner foundation leg and foundation frame will take place. Inlet valve 17 and bleed valve are opened. Marker dye followed by grout is introduced through inlet valve 17 into the chamber formed between the inner foundation leg and the foundation frame. When dye and grout are observed by cameras and / or sensors mounted on the frame, exiting from bleed valve 27 both inlet and bleed valves are closed. The grout is allowed to cure. Seals 25 exclude water from this chamber and hold the grout under pressure. Shear keys 31 and 35 or other features are installed to resist the design loads through the grouted connection.
Alternately a mechanical connection could be used (not shown)
The deployment vessel now returns to the deployment site and the lifting frame is lowered over the installation and drilling frame. Transponders on the installation and drilling frame, lifting frame and foundation frame can be used to assist in positioning the individual assemblies.
The lifting frame incorporates members so that the lifting frame will self align with the installation and drilling frame during lowering and assembly. Furthermore, these alignment members can be arranged so that when the lifting frame and the installation and drilling frame are connected, the alignment members on the lifting frame assist with the alignment and connection of the installation and drilling frame to the foundation frame, for instance in the case where the foundation frame is placed first on the seabed and the installation and drilling frame later, or during decommissioning. The lifting frame is then mechanically connected to the installation and drilling frame. Once the lifting frame has been connected, the mechanical coupling means between the installation and drilling frame and the foundation frame are released and the lifting frame and installation and drilling frame recovered to the deployment vessel. The command vessel can marshal the supply lines during these operations. When the installation and drilling frame and lifting frame have been recovered the vessels can depart the site.
When the installation and drilling frame is disconnected from the foundation frame the installation and drilling frame and the lifting frame can, if required, be used to install the permanent equipment on the foundation frame.
If for example the foundation frame is to be used to support a grid connected tidal stream turbine, the method used would be as follows: Referring to Figures 21 to 28 inclusive, the installation of an electrical connection plate, J-tube and cable will be described.
If the lifting frame is not suitable or cannot be easily modified/adjusted for the proposed operations, the mechanical couplers installed on the lifting frame can be removed and installed in a purpose designed and fabricate installation and alignment frame as follows:

The deployment barge will be towed to a suitable load out location. The installation frame will be lowered to the sea-bed. Mechanical couplers will be operated disconnecting the installation and drilling frame 40 from the lifting frame 42. The lifting frame will now be recovered to the barge.

The mechanical couplers will be removed from the lifting frame 42 and reinstalled into a purpose designed and fabricated alignment and installation frame Figure 43. This installation frame will be winched up under the barge as before.
An electrical connection plate 61, J-tube with articulated joint 62, a length of export cable with a dry mate connector and bend restricting cable protectors pre-installed on the shore end will be lifted into the alignment/installation frame see Figure 21. This assembly will be held in place on the alignment and installation frame by its self-weight and features on the frame and assembly will prevent lateral movement during deployment. Sea fastenings/or stop blocks will be provided for transport to the deployment location.
The dry-mate connector and cable end will be transferred on to the deck of a suitable vessel equipped with cabling equipment. This dry-mate connector and cable will be routed through a cable engine 48 and spooled on to a powered drum 47 on the vessel as shown in Figure 21. The J-tube is held in a horizontal orientation to reduce the requirement for a deep water load out berth and a deep water passage to the deployment site, as would be necessary if it was to be transported in the lowered vertical orientation.
This deployment spread comprising a tug 39, deployment barge 38, installation frame with connectors and cable pre-installed, will be towed to the deployment location. The cabling vessel can travel at a suitable relative position and distance to the barge 38 necessary to maintain a suitable catenary in the cable and so ensure that the ratings of the cable are not exceeded.
Referring to Figure 22, if the tidal and sea and weather conditions at the deployment location are suitable for the operation and once close to the designated foundation or at a sheltered location with sufficient water depth for the remaining portion of the passage, the j-tube will be lowered into the vertical position by a winch on the barge, as shown in Figure 22.
Alternatively, the J tube could be partially lowered and the cabling vessel could control the final lowering of the cable and J tube. The cabling vessel can pay out cable or move position to keep the required tension catenary in the export cable, the cable engine will ensure the required tension is maintained.
The tug will now be positioned close to the foundation and hold station see Figures 21 to 28. The connection plate j-tube and alignment and installation frame will be lowered to a depth such that the alignment guides can contact the central tower. The tug will pay out/recover its tow rope and move the barge so that the installation/alignment frame moves towards the foundation tower. The alignment guides can, if required, use the central tower as a guide to centralise the connection plate over the foundation tower.
Sensors, transducers, cameras, sonar etc. can, if required, be installed on the installation frame this data can be used to confirm the position of the j-tube and connection plate relative to the foundation.
When the connection plate and j-tube are in the correct position, so that the alignment features on the installation frame contacts the foundation tower, it will be further lowered and so mate the connection plate and j-tube with the foundation.
On confirmation that the connection plate and j-tube are correctly aligned and seated the installation frame is further lowered and so disconnects from the connection plate and j-tube. The tug can now adjust the tow line to move the barge and so move the installation frame away from the foundation. Once clear of the foundation the installation frame can be recovered and sea fastened to the barge.
The tug and installation vessel can now depart the site. The cabling vessel can be specified so that it can remain on site throughout the full tidal cycle. If unfavourable weather conditions are forecast the cabling vessel can lay the remaining cable and end connector on to the seabed for recovery later and connection to the export cable.
Alternately, a pre-laid export cable end could be recovered to the vessel deck. The electrical and mechanical connections can be formed and the cable re-laid on the seabed.
Furthermore, referring now to 29 to 45, following the same procedures as described above, a nacelle can be installed on the foundation frame anchored into the seabed. Referring initially to Figure 29, a nacelle installation and alignment frame are installed on the deployment barge as shown in Figure 29.
A nacelle will be lifted from the load out area and placed in the nacelle installation alignment frame.
Alternatively a nacelle or a number of nacelles can be loaded onto a flat top barge, placed in transport frames and transported to an intermediate laydown area at a sheltered location. This laydown area will have sufficient water depth to give overhead clearance for the installation barge. Once at the location the nacelles, and transport frames can be lifted onto the seabed at agreed locations.
The installation barge will now be towed to this intermediate laydown area and hold position over a nacelle. The nacelle installation frame will be lowered from the installation barge and pick up the nacelle from the transportation frame.
The nacelle and installation frame will then be winched up under the barge and sea-fastened. The barge will be towed to its foundation location and hold station close to the tower. Sea-fastenings will now be removed.
As with the cable connection plate and J tube, this nacelle installation frame will be lowered to a depth so that the alignment guides on the installation frame may contact the central tower to act as an installation guide, but not so low that the turbine blades can contact the tower - see Figure 30.
The tug will let out or recover the tow line, and so move the barge so that alignment guides on the installation frame may contact the central tower to guide and centralises the nacelle over the central tower.
The nacelle/installation frame will be now lowered so that the nacelle aligns and seats on the wet-mate connector plate on the on the central tower.
The installation frame is now further lowered to disengage from the nacelle.
The tug will recover/let out its tow line to move the barge and so the recovery frame away from the installed nacelle. Once clear of the nacelle installed on the foundation frame the installation frame can be recovered to the barge.
In another embodiment with reference to figures 37 to 44 a nacelle J tube and export cable could be installed in a single operation. This would have the advantage of removing the need to provide, install and maintain a wet mate electrical connection, but would have the disadvantage of requiring significant cabling works to disconnect and handle the export cable before a nacelle is removed or exchanged.
These or similar procedures can be used to swap out nacelles or cabling during planned maintains of the turbine or to effect repairs caused by breakdowns or mechanical damage.
For removal of the nacelle or other equipment, the alignment and installation frame will be positioned close to the foundation frame, at a depth so that the frame can contact the central tower of the foundation frame but pass under the apparatus to be removed. When the alignment and installation frame contacts the central tower the deployment vessel will maintain position. The installation and recovery frame can now be raised and features on the frame and apparatus will guide the installation frame and engage with the apparatus. Sensors on the alignment and installation frame will verify that the correct engagement has taken place. The installation frame can be further raised so removing it from the tower. It can now be raised and sea-fastened to the deployment vessel.
At the end of the service life of the foundation frame, all the equipment is removed using the same methods as described above, to leave the foundation frame as it was installed. The installation equipment is mobilised and the lifting frame and installation and drilling frame are once more lowered over the foundation frame. The lifting frame and installation and drilling frame are mechanically connected to the foundation frame using mechanical couplings 14. A shaped explosive charge is installed by ROV into the decommissioning duct 18 and the duct sealed. If required hydraulic pressure is applied to the jack legs 2 to apply an upward force on the foundation frame. The explosive charge is detonated remotely and the anchor bars severed. The foundation frame, installation and drilling frame and lifting frame are then recovered to the decommissioning vessel.
Thus, features of the system of the present invention are as follows:

1. Hollow "self drilling" anchor; by "self drilling" is meant that the anchor is provided with drilling means which operate to put the anchor under tension.
2. Suitable for a variety of sites and foundations.
3. Remotely operated so capable of operating in any water depth.
4. No fixed anchor length.
5. Levelling foot detail cylinder that can roll.
6. Can be configured as single drill string, tripod, or multiple drill strings.
7. Adjustable jack legs.
8. Accumulators to reduce shock loading.
9. Accumulators in hydraulic supply lines to absorb back pressure in umbilicals,
10. ALL anchors are tested and preloaded so that the anchor loads during their service life are higher than the maximum design working load so eliminated cyclic loading and reducing fatigue.
11. Grout bags to fill gap between foot and seabed to transfer loads and prevent further penetration into seabed.
12. Grout bags to prevent scour.
13. Gussets plates to limit the penetration of the foot into the seabed.
14. Self alignment members.
15. Duct for explosive charge during decommissioning.
16. In an alternative embodiment, a chemical anchor instead of grout can be pre-installed on the installation and drilling frame.

The advantages of the system and method of the invention are as follows:

1. Tension anchors.
2. Installation and drilling frame designed so that it will act as a gravity structure and keep the foundation frame on the sea bed even before any drilling takes place.
3. The installation of self-drilling tension foundations.
4. The application of proof loading and pre loading of the tension anchor to prove the suitability of the anchor and reduced the cyclic loading and so fatigue.
5. The ability to apply a load to the anchorage over and above that which it will experience during its service life.
6. The ability to force the foundation frame into rock to provide resistance to shear loads.
7. Smaller diameter anchor holes are achieved thereby resulting in less spoil deposited in the sea-bed / water column. Since mostly small diameter anchor holes are required, this brings about the subsequent reduction in arisings from the drilling operation. The ability to easily change the length and diameter of the anchor rod to suit a wide variety of seabed and foundations.
8. The ability to install tubular hollow section anchors using DHH technology.
9. Use the environmental conditions, tidal velocity and direction etc., to assist with the alignment of the various subassemblies during the operations.

The system and method of the present invention are particularly advantageous where the bed comprises a rocky or hard material and levelling of the installation and drilling frame is particularly problematic combined with technical difficulties of providing a foundation frame.

1. In this embodiment, the foundation frame comprises a three legged foundation frame provided with a central support column.
2. The sequences of operations for deploying the foundation frame are as follows:
3. The foundation frame, installation and drilling frame with drill strings preinstalled is commissioned and lifted onto the seabed at a suitable sheltered location.
4. The deliver vessel is positioned over the foundation frame and the installation and drilling frame and a lifting frame is lowered over the installation and drilling frame and the foundation frame.
5. The lifting frame will "self-align" with the installation and drilling frame. By the term, "self-align" is meant that the lifting frame is provided with alignment guide members 64 (as shown in for instance Figure 46) that will, under the weight of the frame, contact the foundation frame, and rotate and guide the mechanical couplers 63 towards the lifting points on the installation and drilling frame. Additional funnels/guides on top of the lifting tubes will assist with the final alignment and guiding of the lifting couplers into place. Now, with the lifting frame aligned with the installation and drilling frame. The lifting devices are operated so that the installation and drilling frame and the foundation frame are connected to the barge.
6. The three winches on the barge will be operated and the installation and drilling frame and the foundation frame are raised underneath the barge and sea-fastened.
7. The umbilical lines, hydraulic lines and grout lines are transferred from the quayside and transferred to the command vessel.
8. The installation spread will comprise a tug boat for pulling a barge capable of heavy lifting; the heavy lift barge with the foundation frame, installation and drilling frame and the lifting frame under-slung and sea-fastened and the command vessel with the required generators hydraulic power packs and grout batching and pumping equipment.
9. The installation spread will be towed to the deployment location. The sea-fastenings will be disconnected and the foundation frame and the installation and drilling frame lowered to the seabed using the lifting frame and the three winches on the barge.
10. On confirmation that the location, heading, water depth etc. are within tolerances from data received from sensors attached on the installation and drilling frame, the mechanical couplings between the lifting frame and the installation and drilling frame will be disconnected. The lifting frame will then be recovered to the underside of the barge.
11. The tug will then tow the barge away from the deployment site and stand by.
12. Using power packs and command and control systems on the command vessel, the installation and drilling frame will be levelled. Following confirmation from sensors on the installation and drilling frame, that the installation and drilling frame and the foundation frame are within tolerance, the plurality of drill head 34 (see Figure 46), in which three drill heads 34 are shown) will be operated. These drilling operations can be carried out concurrently or singly dependant on the required time frame and the number and ratings of the power packs on the command vessel and umbilicals connecting the vessel to the installation and drilling frame.
13. The fluid required for flushing the drill arises from the hole, can comprise air or water supplied from the command vessel or water supplied from an under-water pump on the installation and drilling frame. Drilling progress, flushing fluid pressure, removal of arises and debris can be monitored and adjusted from instrumentation on the installation and drilling frame receiving information supplied by sensors on the installation and drilling frame.
14. The drilling arises will be expelled through arise exhaust duct 26 to the sea bed. If required, this exhaust duct can be extended back up to the command vessel where these arises could be collected for disposal. The function of conductor shoe 21 is to form a path for the arises at the interface between the sea-bed and the rock and stop arises filling the space between the penetrating shoe 24 and the bottom of the jacking chamber bearing plate 19. The function of seal 25 is to prevent drilling arises entering the area above the jacking chamber and possibly preventing good contact between the anchor head stop block 3 and the stressing stool 29.
15. When the anchor head stop block 3 on the drill string makes contacts the top of the stressing stool 29 on the foundation frame 33, the drilling operation for that anchor will be complete.
16. A predetermined quantity of grout will be introduced from the command vessel, through valve block 17, grout line 8, side entry swivel 10, the open centre of the drill string, the drill string anchor head and into the space between the drilled hole and the drill string. Alternately, epoxy compound could be mixed and placed from batching equipment mounted on the installation and drilling frame, so reducing the length of the delivery lines and quantity of chemical anchor required.
17. This process is repeated for the remaining drill strings.
18. Following sufficient curing of the grout, determined by water temperature rock temperature grout strength determined by crush tests and required test loads required, water is introduced into jacking chamber 28 through valve block 17. Bleed valve 27 is then closed and the water pressure increased until the load exerted between the stressing stool 29 and the anchor stop block 3 has reached the proof load required for the application. The proof load is the load that the anchor can accept without damage to the anchor, solidifying material (for example, grout), bond or rock or anything else in the load path. If an anchor is correctly installed, applying the proof load, be it 1.5 or 2 times the design working load will not damage the anchor. The water pressure can be adjusted so that a test cycle for the anchor can be carried out to the specification. If bleed valve 27 and valve block 17 are both closed, pressure sensors on the jacking chamber will show that the required loads on the anchors can be maintained.
19. A further effect of stressing the anchors will be to force the penetrating shoe into the seabed.
20. When all anchors have been proof tested, bleed valves 27 will be opened and the load on the anchors reduced to the designed working load plus a predetermined amount to ensure the anchor does not become un-stressed during its service life, which could result in fatigue stresses in the anchors.
21. Grout will be introduced into grout bags 20 to fill any gap between the bearing plate 19 and the seabed.
22. Valve block 17 and bleed valve 27 will be opened and grout will be introduced into jacking chamber 28 forcing the water out of the chamber. A marker dye may be introduced before the grout to aid confirmation that the complete removal of the water in the chamber. When dye/grout are confirmed exiting from bleed valve 27 this valve will be closed and the grout pressure increased so that the load in the anchor reaches the required figure. Valve block 17 will be closed and the load in the anchor monitored.
23. These operations will be repeated for the remaining anchor bars.
24. Grout will be introduced into the gap between the telescoping section of the leg and the foundation frame or a ratchet/threaded section will be operated by a ram on the installation and drilling frame. More detail and a drawing of this section need to be done.
25. Referring to Figure 46, when all anchor bars have been tested and preloaded the barge and lifting frame is remobilised to the deployment site, the lifting frame 42 will be lowered over the installation and drilling frames so that mechanical coupling means 63 engage with their lifting points. The mechanical coupling means 63 are then engaged and the mechanical coupling means 14 opened. The installation and drilling frame is winched under the barge leaving the foundation frame connected to the seabed. The barge will be towed to the load-out location and the next foundation frame/anchors etc. fitted alternatively, the installation and drilling frame is lowered to the sea-bed at a suitable location. Mechanical coupling means 63 is operated thereby disconnecting the installation drilling frame 40 from the lifting frame 42 foundation frame. The lifting frame will be recovered to the underside of the barge.
26. The mechanical coupling means 63 will be disconnected from lifting frame 42 and installed into nacelle/electrical connection plate alignment/installation frame. The nacelle installation and drilling frame is winched up under the barge as shown in Figure 21.
27. A wet-mate connection plate, j-tube with articulated joint, and a length of export cable with a dry mate connector installed on the shore end will be lifted in to the alignment/installation frame as shown in Figure 21.
28. The dry-mate connector and cable end will be passed on to a vessel equipped with cabling equipment. This dry-mate connector and cable will be spooled on to a powered drum on the cabling vessel as shown in Figure 21.
29. The deployment spread comprising a tug, deployment barge, installation frame connectors and cable and cabling vessel will be towed to the deployment location. Once close to the designated foundation frame or in a sheltered local location with sufficient water depth on route, between this location and the foundation frame, the j-tube will be lowered to vertical position see Figure 22. The cabling vessel can pay out cable or move position to keep the export cable in the correct tension. The tug will be positioned up tide from the foundation frame and hold station. The connection plate j-tube and alignment and installation frame will be lowered to a depth that the alignment guides can contact the central tower. The tug will pay out its tow rope and move the installation frame towards the foundation frame. The alignment guides can use the central tower to guide and centralise the connection plate over the foundation frame tower. Sensors, cameras and sonar on the installation frame will confirm the position of the j-tube and connection plate relative to the foundation frame.
30. When the connection plate and j-tube are in the correct position the installation frame will be lowered installing the connection plate and j-tube on the foundation frame. The cabling vessel can move position or pay out cable to keep the export cable in the correct tension.
31. On confirmation that the connection plate and j-tube are correctly seated the installation frame is further lowered and disconnected from the connection plate and j-tube. The tug can recover tow line to disengage the installation from the foundation frame. Once clear of the foundation frame the installation frame can be recovered and sea fastened to the barge.
32. The installation barge can be towed to the load out area to collect the next electrical connection and cabling assembly or demobilised.
33. The cabling vessel can now lay the remaining cable on to the seabed or recover a pre-laid export cable with connector to the vessel deck. The electrical and mechanical coupling means can be formed and the cable laid on the seabed.
34. A nacelle installation and alignment frame will be installed on the deployment barge as shown in Figure 29.
35. A nacelle will be lifted from the load out quay and placed in the nacelle installation alignment frame.
36. Alternatively a nacelle or any number of nacelles will be loaded onto a flat top barge, placed in transport frames and transported to an intermediate laydown area at a sheltered location. This laydown area will have sufficient water depth to give overhead clearance for the installation barge. Once at the location, the nacelles and transport frames will be lifted on top the seabed at agreed locations.
37. The installation barge will be towed to the intermediate laydown area and manoeuvre over a nacelle and hold station over the nacelle. The nacelle installation frame will be lowered from the installation barge and pick up the nacelle.
38. The nacelle and installation frame will be winched up under the barge and sea-fastened.
39. The barge will be towed to its foundation frame location and hold station close to the tower and sea-fastenings removed.
40. The installation and drilling frame will be lowered so that the alignment guides on the installation and drilling frame are low enough to contact the central tower to act as an installation guide, but not low enough for the turbine blades to contact the tower as shown in Figures 32 and 33.
41. The installation tug will let out or recover the tow line, connected to the installation barge, so that alignment guides contact the central tower to guide and centralises the nacelle over the central tower.
42. The nacelle/installation frame will be further lowered so that the nacelle aligns and seats on the wet-mate connector plate on the on the central tower.
43. The installation frame is then lowered and disengaged from the nacelle.
44. The tug will recover/let out its tow line to move the barge and so move the recovery frame away from the installed nacelle. Once clear of the foundation frame/nacelle, the installation frame 43 can be recovered to the barge.

Claims

A system for installing a foundation for a subsea structure wherein the system comprises a foundation frame (16) which is provided with anchoring means comprising at least one tension anchor and means for fixing said at least one tension anchor into the seabed; and the system also comprising means for controlling the operation of the foundation frame; the foundation frame being adapted to support and be removably connected with apparatus such as energy conversion apparatus, wherein, in use, the anchoring means is operated to become embedded in the seabed; wherein the system comprises an installation and drilling frame carrying drilling means; the installation and drilling frame providing sufficient weight to enable the system to act as a gravity foundation while the installation is taking place; the installation and drilling frame being removably connectable to the foundation frame.
A system for installing a subsea foundation on the seabed as claimed in Claim 1; wherein the system comprises means for pre-loading or proof loading to test the suitability of the anchor; optionally wherein the foundation frame structure is used as the locating template for the drilling equipment in order to achieve accurate positioning of the tension anchors.
A system for installing a foundation for a subsea structure as claimed in any preceding Claim wherein the means for embedding said at least one tension anchor comprises the foundation frame; and the installation and drilling frame; optionally wherein the foundation frame structure is used as the locating template for the drilling equipment in order to achieve accurate positioning of the tension anchors; optionally wherein a single tension anchor or multiple tension anchors are provided; and optionally wherein the tension anchor comprises a hollow tubular anchor.
A system for installing a foundation for a subsea structure as claimed in Claim 3 wherein the at least one tension anchor foundation is configured to incorporate means for installation of the hollow tubular anchor, said means for installation of the anchor in the seabed comprising a "down the hole" hammer (53) and a detachable drill head.
A system for installing a foundation for a subsea structure as claimed in any preceding claim wherein the at least one tension anchor is provided with means for embedding said at least one tension anchor in the seabed, said means for embedding the at least one tension anchor comprising drilling means, optionally wherein the drilling means comprising means for moving a drill carriage up and down a drill mast; optionally wherein the means for embedding said at least one tension anchor in the seabed further comprises the drill carriage on which a drill drifter or rotary drive head is mounted; optionally wherein the means for moving a drill carriage up and down a drill mast comprises a ram and pulley arrangement used to move the drill carriage up and down the drill mast; and optionally wherein the diameter and or length of the anchor bar and of the bond length into the seabed can be adjusted to suit a wide variety of ground conditions; and optionally wherein the foundation frame is adapted to carry any number of drill strings (13, 22).
A system for installing foundations for subsea structures as claimed in any preceding claim wherein the system includes a lifting frame (42) with geometrically interlocking guides for lowering and raising the assembled frames/foundation frame to the seabed; optionally wherein the lifting frame for lowering and raising the assembled frames/foundation frame to the seabed comprises a three point lifting arrangement; optionally wherein the installation and drilling frame incorporates levelling means such that the installation and drilling frame will be adjusted to level by command signals given from the command vessel; optionally wherein includes levelling means comprising a plurality of landing and levelling legs (34) adapted such that the landing and levelling legs touch the seabed before the drill string carried on the foundation frame; optionally wherein shock absorption is incorporated into the landing/levelling legs by incorporating hydraulic accumulators (2) and valves thereby reducing shock loads on the lowering equipment.
A system for installing foundations for subsea structures as claimed in any one of the preceding claims wherein means are provided in the foundation frame legs for adjusting the length of each leg so as to compensate for unevenness or slopes in the seabed; optionally wherein the means provided in the foundation frame legs for adjusting the length of each leg so as to compensate for unevenness or slopes in the seabed comprise a mechanical ratchet.
A system for installing foundations for subsea structures as claimed in any one of Claims 3 to 7 wherein the installation and drilling frame and consequently the foundation frame to which it is connected can be levelled and if required, lowered until the foundation frame bearing plate (19) touches the seabed by adjusting the hydraulic pressure flow in the hydraulic rams built into the installation and drilling frame legs.
A system for installing foundations for subsea structures as claimed in any one of Claims 3 to 8 wherein hydraulic oil pressure/flow can be supplied from either hydraulic power packs and valves built into the installation and drilling frame or through hoses from hydraulic power packs on the command and control vessel (37); optionally wherein the alignment and level of the foundation frame can also be determined from the command vessel to confirm that it is within the required specification.
A system for installing foundations for subsea structures as claimed in Claim 5 wherein the drilling means comprise a drill string comprising a hydraulic rotary drifter head (5), an entry port for introducing flushing fluid and solidifying anchors material to the anchor, a stop means optionally comprising a stop block on the anchor to transfer the jacking loads from the anchor bar to a stressing stool (29), a hollow centre anchor bar, a drill bit, hydraulic clamps to grip the anchor and a system to raise and lower the drill string is pre-installed on the installation and drilling frame; optionally, the power lines, grout lines (8) and flushing line (9) required to operate the drill system are marshalled inside the outer casing using retractable cables;
optionally, using the rotary percussive drifter head, the drill bit forms a hole in the seabed and concurrently drives the conductor shoe (21) into the seabed until the conductor shoe reaches its end stop (32);
optionally, shear keys (31) in the conductor shoe then break off or deform allowing the drill bit and anchor to continue with forming the anchor hole;
optionally, as the anchor is drilled into the seabed, the drill arisings are flushed out of the drilled hole along the drill conductor (23) and exit through the exhaust duct (26) into the water column;
optionally, the flushing medium, preferably sea water, is supplied from a water pump (12) mounted on the installation and drilling frame but alternatively water, weak grout mix, drilling mud or air from the command and control vessel could also be supplied for the same function; and
optionally, drilling continues until the stop block on the anchor bar contacts the stressing stool top plate.
A system for installing foundations for subsea structures as claimed in any one of the preceding claims wherein the anchor bar comprises a central channel through which a solidifying anchoring material can be introduced for flowing through the control channel and out of the anchor bar into the area surrounding the anchor bar where the solidifying anchoring material changes from being in fluid form to being in solid form so as to embed the anchor bar in the seabed, optionally wherein the solidifying anchoring material comprises cementatitious grout which is introduced into the central channel in the anchor bar through a grout line; optionally wherein chemical anchor dosing, mixing, installation equipment with the associated power packs, pipe work and valves can be installed on the installation and drilling frame.
A system for installing foundations for subsea structures as claimed in any preceding claim wherein the means for embedding the tension anchor in the seabed further comprises a stop block on the anchor bar and a moveable stressing stool for transferring the load through the anchor bar into the anchorage point on the seabed effective to force the foundation frame penetrating shoe (24) into the seabed and means for controlling the force applied.
A system for installing foundations for subsea structures as claimed in Claim 12 wherein grout bags (20) are preinstalled in the bottom of the foundation frame at mechanical clamp/connection and means for inflating the grout bags are provided so that in use, the pre-installed grout bags can be inflated and so fill any voids remaining between the bottom of the foundation frame and the seabed whereby this grout, when cured resists any further penetration of the foundation frame foot into the seabed and provide scour (erosion) protection at the base of the foundation frame.
A method for installing foundations in the seabed, the method comprising the following step:
providing an apparatus for installing foundations to subsea structures with at least one tension anchor and providing the apparatus with means for embedding said at least one tension anchor into the seabed, the apparatus comprising a foundation frame which is provided with anchoring means, the foundation frame being adapted to support and be removably connected with equipment such as energy conversion apparatus and the anchoring means, in use, being embedded in the seabed; and providing the apparatus with an installation and drilling frame carrying drilling means; the installation and drilling frame being removably connectable to the foundation frame; the means for embedding said at least one tension anchor comprises the foundation frame; and the installation and drilling frame; optionally wherein the method also comprises the following step:
providing the tension anchor as a hollow tubular anchor, wherein the at least one tension anchor foundation is configured to incorporate a "down the hole" hammer and a detachable drill head for installation of the hollow tubular anchor in the seabed.
A method for installing foundations in the seabed as claimed in claim 14, the method comprising the following steps:
connecting the foundation frame to the installation and drilling frame;
(a) installing the drill string(s) onto the foundation frame; and the installation and drilling frame and lifting the foundation frame; and the installation and drilling frame with drill string(s) installed, onto the seabed at a suitable sheltered location;

(b) manoeuvring/positioning a delivery vessel over the foundation frame; and the installation and drilling frame;

(c) lowering a lifting frame over the installation and drilling frame and the foundation frame;

(d) aligning the lifting frame with the installation and drilling frame;

(e) operating lifting devices so that the installation and drilling frame and the foundation frame are connected to a barge (38) for deploying the installation and drilling frame and the foundation frame to the desired site;

(f) operating the winches on the barge so as to position the installation and drilling frame and the foundation frame underneath the barge and sea-fastening the frames underneath the barge;

(g) transferring the umbilical lines (50), hydraulic lines and grout lines from the quayside and transferred to the command vessel;

(h) towing the installation and drilling frame and the foundation frame to the deployment location; and

(i) At the deployment location, disconnecting the sea-fastenings and lowering the foundation frame and the installation and drilling frame to the seabed by operating the lifting frame and winches on the barge; optionally carrying out drilling operation so as to embed in the seabed, the at least one tension anchor provided on the foundation frame; and optionally the method comprising the following further step: operating the tug (39) to tow the barge away from the deployment site and having the tug standing by at a location remote from the deployment location.
A method for installing foundations in the seabed as claimed in any one of Claims 14 or 15, the method comprising the following further steps:
introducing a predetermined amount of grouting material to the region around the tension anchor which is embedded in the seabed;

following sufficient curing of the grout, introducing water into a jacking chamber (28); and

closing a bleed valve (27) on the jacking chamber and increasing the water pressure until the load exerted between the stressing stool and the anchor stop block has reached the predetermined proof load; thereby stressing the or each tension anchor so as to force the penetrating shoe into the seabed.
A method for installing foundations in the seabed as claimed in any one of Claims 14 to 16, the method comprising the following further steps before stressing the or each anchor so as to force the penetrating shoe into the seabed:
adjusting the water pressure in the jacking chamber by the operating the bleed valve and carrying out a test cycle for the or each tension anchor;
and when all anchors have been proof tested, opening the bleed valves and reducing the load on the anchors reduced to the designed working load plus a predetermined amount to ensure the anchor does not become un-stressed during service, which could result in fatigue stresses in the anchors; optionally wherein the method comprises the following further step:
introducing grout into the gap between the telescoping section of the leg and the foundation frame or a ratchet/threaded section will be operated by a ram on the installation and drilling frame (40).
A method for installing foundations in the seabed as claimed in Claim 16 wherein the method comprises the following further steps:
when all anchor bars have been tested and preloaded, transporting the barge and lifting frame to the deployment site;

lowering the lifting frame over the installation and drilling frames so that mechanical coupling means engage with the lifting points on the installation and drilling frame;

engaging the mechanical coupling means so that the mechanical coupling means are opened;

winching the installation and drilling frame under the barge thereby leaving the foundation frame connected to the seabed;

towing the barge to the load-out location and fitting the next foundation frame/anchors;

alternatively, lowering the installation and drilling frame to the sea-bed at a suitable location;

operating the mechanical coupling means thereby disconnecting the installation drilling frame from the lifting frame foundation frame;

recovering the lifting frame to the underside of the barge;

disconnecting the mechanical coupling means from the lifting frame and installing the mechanical coupling means into the nacelle/electrical connection plate/alignment/installation and drilling frame; and

winching the nacelle installation (46) and drilling frame up under the barge.
A method for installing foundations in the seabed as claimed in Claim 16 wherein the method comprises the following further steps:
installing a wet-mate connection plate, j-tube with articulated joint, and a length of export cable with a dry mate connector installed on the shore end and lifting into alignment with the installation and drilling frame;

passing the dry-mate connector and cable end on to a vessel equipped with cabling equipment, with the dry-mate connector and cable being spooled on to a powered drum on the cabling vessel;

towing the deployment spread comprising a tug, deployment barge, installation and drilling frame connectors and cable and cabling vessel (51) to the deployment location;

once close to the designated foundation frame or in a sheltered local location with sufficient water depth on route, between this location and the foundation frame, lowering the j-tube to vertical position;

paying out cable from the cabling vessel or moving position to keep the export cable in the correct tension;

positioning the tug up tide from the foundation frame and hold station;

lowering the connection plate j-tube and alignment and installation and drilling frame to a depth that the alignment guides (15) can contact the central tower;

paying out tow rope from the tug and moving the installation and drilling frame towards the foundation frame;

operating the alignment guides to guide and centralise the connection plate over the foundation frame tower; and

confirming the position of the j-tube and connection plate relative to the foundation frame using sensors, cameras and sonar on the installation and drilling frame.
A method for installing foundations in the seabed as claimed in Claim 18 or 19 wherein the method comprises the following further steps:
when the connection plate and j-tube are in the correct position, lowering the installation and drilling frame and installing the connection plate and j-tube on the foundation frame;

keeping the export cable in the correct tension by paying out cable or moving the position of the cabling vessel;

on confirmation that the connection plate and j-tube are correctly seated, further powering the installation and drilling frame and disconnecting from the connection plate and j-tube;

disengaging the installation from the foundation frame;

once clear of the foundation frame, the installation and drilling frame can be recovered and sea fastened to the barge;

optionally, the installation barge can be towed to the load out area to collect the next connection and cabling assembly or demobilised; and

the cabling vessel can now lay the remaining cable on to the seabed or recover a pre-laid export cable with connector to the vessel deck; the electrical and mechanical coupling means can be formed and the cable laid on the seabed;

installing a nacelle installation and alignment frame on the deployment barge; lifting a nacelle from the load out quay and placed in the nacelle installation alignment frame;

optionally, alternatively a nacelle or any number of nacelles will be loaded onto a flat top barge, placed in transport frames and transported to an intermediate laydown area at a sheltered location, this laydown area having sufficient water depth to give overhead clearance for the installation barge; once at the location, the nacelles and transport frames will be lifted on top the seabed at agreed locations;

towing the installation barge to the intermediate laydown area and manoeuvring over a nacelle and hold station over the nacelle; lowering the nacelle installation and drilling frame from the installation barge and picking up the nacelle; and

winching the nacelle and installation and drilling frame up under the barge and sea-fastened;

towing the barge to its foundation frame location and hold station close to the tower and removing the sea-fastenings;

lowering the installation and drilling frame so that the alignment guides on the installation and drilling frame are low enough to contact the central tower to act as an installation guide, but not low enough for the turbine blades to contact the tower;

letting out or recovering the tow line, connected to the installation barge, so that alignment guides contact the central tower to guide and centralises the nacelle over the central tower;

further lowering the nacelle/installation and drilling frame so that the nacelle aligns and seats on the wet-mate connector plate on the on the central tower;

lowering the installation and drilling frame and disengageing from the nacelle; and the tug will recover/let out its tow line to move the barge and so the recovery frame away from the installed nacelle; and once clear of the foundation frame/nacelle, the installation and drilling frame can be recovered to the barge.