EP-4739570-A1 - APPARATUS AND METHOD FOR SUBSEA MOORING

Abstract

An apparatus (1) and method for Subsea Mooring are provided. The apparatus (1) includes a downwardly extending arrangement of at least two and preferably three legs (2a, 2b, 2c). A drill bit (8a, 8b, 8c) is coupled to each respective leg (2a, 2b, 2c), and each said drill bit (8a, 8b, 8c) is configured for drilling into a seabed (51). At least one of said drill bits (8a, 8b, 8c) is configured to rotate in a first direction whilst drilling into the seabed (51) and at least one other of said drill bits (8a, 8b, 8c) is configured to rotate in a second direction, opposite to said first direction. Both said at least one and said at least one other of the drill bits (8a, 8b, 8c) are arranged to simultaneously drill into the seabed (51).

Inventors

• GASKIN, KEITH

Assignees

• Renewable Energy Mooring Solutions Limited

Dates

Publication Date

20260513

Application Date

20240625

Claims (20)

1. 1. A subsea mooring apparatus comprising: a downwardly extending arrangement of at least two legs; and a drill bit coupled to each respective leg, wherein each said drill bit is configured for drilling into a seabed; and wherein at least one of said drill bits is configured to rotate in a first direction whilst drilling into the seabed and at least one other of said drill bits is configured to rotate in a second direction, opposite to said first direction, whilst drilling into the seabed.
2. 2. A subsea mooring apparatus according to claim 1, further comprising a frame, wherein the arrangement of legs extend downwardly from the frame.
3. 3. A subsea mooring apparatus according to claim 1 , further comprising at least one connecting mechanism for coupling the apparatus to a mooring tether used to couple an offshore wind turbine to the apparatus.
4. 4. A subsea mooring apparatus according to any preceding claim, wherein the said drill bit is coupled to a lower end of each respective leg.
5. 5. A subsea mooring apparatus according to any preceding claim, wherein the rotation of each drill bit is driven by seawater by a pumping mechanism, to a higher pressure than the pressure of seawater taken from the sea at the location of use of the apparatus.
6. 6. A subsea mooring apparatus according to claim 5, wherein the apparatus further comprises at least one fluid inlet and wherein said fluid is pumped from a vessel via at least one umbilical pipe by the pumping mechanism to said at least one fluid inlet.
7. 7. A subsea mooring apparatus according to claim 6, wherein each leg comprises a conduit for conveying the pressurised fluid from the said at least one fluid inlet to the drill bit of each leg.
8. 8. A subsea mooring apparatus according to any of claims 5 to 7, wherein each of the legs comprises a motive device associated with each respective drill bit, wherein said motive device is configured to translate hydraulic pressure/power and flow from the pressurised fluid into rotational energy to rotate the drill bits.
9. 9. A subsea mooring apparatus according to any of claims 5 to 8, wherein each leg comprises a fluid motor and each drill bit is rotated by a fluid motor disposed in fluid communication with the conduit of each leg, wherein each fluid motor comprises a rotor and a stator and said stator comprises one or more sets of nozzles.
10. 10. A subsea mooring apparatus according to claim 9, wherein each leg is arranged such that fluid conveyed through the conduit flows through the fluid motor of each leg, flowing through one or more sets of nozzles within the stator and therein driving rotation of the rotor.
11. 11. A subsea mooring apparatus according to of claim 10, wherein the rotor is rotationally connected to the drill bit, such that rotation of the rotor is configured to rotate the drill bit.
12. 12. A subsea mooring apparatus according to any of claims 5 to 8, wherein each leg comprises a Positive Displacement Motor (PDM) and each leg is arranged such that fluid conveyed through the conduit flows through a PDM of each leg, flowing through a cavity between a rotor and a stator of the PDM and therein driving rotation of the PDM rotor.
13. 13. A subsea mooring apparatus according to claim 12, wherein the rotor is rotationally connected to the drill bit, such that rotation of the rotor is configured to rotate the drill bit.
14. 14. A subsea mooring apparatus according to any preceding claim, wherein the drill bit of each respective leg comprises a cross sectional surface area that is greater than any other cross-sectional area of said respective leg, such that the drill bit coupled to each respective leg is configured to drill a throughbore defining an annulus between: an outer surface of each leg of each respective drill bit; and the inner surface of said throughbore drilled by the drill bit.
15. 15. A subsea mooring apparatus according to any preceding claim, wherein the said first direction is clockwise and the said second direction is anti-clockwise.
16. 16. A subsea mooring apparatus according to any preceding claim, wherein at least one first leg comprises an inversed rotational arrangement relative to a rotational arrangement of at least one second leg, such that rotation of the inversed rotational arrangement of said first leg is in said first direction and rotation of the rotational arrangement of said second leg is in said second direction.
17. 17. A subsea mooring apparatus according to any preceding claim, wherein at least one leg comprises a motive device configured to rotate in a first direction and at least one leg comprises a motive device configured to rotate in a second opposite direction.
18. 18. A subsea mooring apparatus according to any preceding claim, wherein the conduits of each of the legs are in fluid communication such that the pressure is substantially equalised in the conduits of each leg.
19. 19. A subsea mooring apparatus according to any preceding claim, wherein at least two of the drill bits are operable to drill simultaneously.
20. 20. A subsea mooring apparatus according to any preceding claim, wherein said at least one of said drill bits is configured to rotate in the first direction whilst drilling into the seabed and said at least one other of said drill bits is configured to rotate in the second direction, (opposite to said first direction), whilst both said at least one and said at least one other of the drill bits are simultaneously drilling into the seabed.

Description

TITLE “Apparatus and Method for Subsea Mooring” FIELD OF THE INVENTION The present invention relates to an apparatus that is used to lay or provide a foundation for the subsea mooring or anchoring of large structures such as offshore floating wind turbines or other large floating structures. BACKGROUND TO THE INVENTION The world's rapidly growing population and the accumulating requirement for energy, in addition to the detrimental environmental repercussions caused by fossil fuel use, have triggered an urgent global demand for alternative energy sources. Wind energy is emerging as a promising substitute due to the numerous advantages that wind energy presents over conventional fossil fuel energy sources. Wind turbines have the potential to offer an eco-friendly solution towards satisfying the ever-growing global demand for alternative energy sources, as they do not emit any of the pollutants responsible for climate change, such as harmful greenhouse gases. Exploiting wind power energy sources mitigates our dependency on fossil fuels, as a result cutting emissions of carbon dioxide and fine particles, as well as other climatealtering substances that contribute to the greenhouse effect. Furthermore, wind is an abundant source of energy that is unlimited over time, inexhaustible and accessible to a large extent on all of the Earth's surface. Performance levels of the transformation of wind energy to electricity have already accomplished remarkable degree of efficiency, achieving efficiency ranges of approximately 40% to 50%; converging towards the maximum theoretical level, which according to Betz’s law is 59%. This impressive level of efficiency, along with the relatively low operational costs make them economically viable as well. After a wind turbine is installed, it requires only minimal maintenance in comparison to other energy sources. Moreover, wind energy could help achieve energy self-sufficiency, providing unquestionable economic benefits to those countries which adopt it, whilst also taking a step towards sustainable development. Offshore wind turbines present several advantages over onshore installations. The wind energy potential of onshore wind turbines portrays a high degree of variability. In stark contrast, offshore wind offers consistent, dependable and stronger, yet less turbulent, wind resources. In order to harness the full potential of wind energy, engineers and inventors have devised various designs and features of offshore wind turbines to cater to specific locations and meteorological conditions. The two main types of offshore wind turbines are “Fixed-bottom” and “Floating” offshore wind turbines. Fixed-bottom offshore wind turbines generally comprise of a steel monopole foundation secured to the seafloor and are by and large only suitable for offshore locations with relatively shallow waters so that foundations can be secured to the seabed. Floating offshore wind turbines on the other hand comprise of a floating structure anchored to the seafloor, they are suitable for relatively deep offshore waters and are therefore particularly useful for wind farm projects deployed far from the shore. At the present moment Fixed-bottom offshore wind turbines are the considerably more prevalent of these two main types. Almost all currently operating offshore wind farms employ fixed foundation turbines, aside from of a few pilot projects. Although offshore wind power is particularly more challenging and expensive than onshore counterparts, the abundance and consistency of wind in the open ocean may offset these difficulties. That being said there is a very apparent requirement for enhancements of the present approaches to installation of offshore wind turbines to be made and a subsequent cost reduction in order for offshore wind turbines to become a viable and attractive solution to investors and companies within the energy sector. Energy sources that are economically viable inherently attract investments from private companies and governments. Accelerated installation will make offshore wind turbines more competitive with the other sources of energy, such as fossil fuels. One crucial barrier to the widespread adoption of offshore wind energy is the relatively high cost of installation of the turbines and in particular the towers on which they are supported. The installation of offshore wind turbines can be slow, usually requiring great amounts of resources and time. One of the particularly high cost components of the installation of offshore wind turbines relates to the excessive time that current methods necessitate. Installation takes up a significant proportion of the costs associated with offshore wind turbines as the process of installing the offshore wind turbines requires the use of specialized resources, such as vessels, equipment and personnel. Logistically, large expenses are therefore incurred when deploying these resources. Accelerated installation time will inevitably result in a