Section of NW Hutton Platform
(Click to Enlarge)
Cutting Underwater Technologies (CUT UK), a specialist cutting services provider to the decommissioning and abandonment industry, developed new machines and methodologies to complete a project worth a seven-figure sum as part of the partial removal (down to the top of the footing) of the North West Hutton Platform situated 130Km North East of the Shetland Islands in the UK Sector of the North Sea.
The work was commissioned by Heerema Marine Contractors and involved CUT using its innovative diamond wire technology to make 77 separate cuts, including those of the massive Corner Legs, 120in OD x 2.75in Wall Thickness (including 14 grout and vent lines) the two Launch Runners Legs and other jacket structural members.
CUT utilised four specialised Diamond Wire Cutting Machines (DWCM) of 10, 18, 30 and 50 inch cutting capacity along with the custom-built 60–120 inch Modular DWCM. After the completion of the design and fabrication works for the Modular DWCM, extensive onshore tests were carried out to assess the efficiency of this new design. Specimens for the 120in Corner Legs, including all internal piping, and for the 55in Launch Runner Legs, 65in to include steel boxes and wood, were supplied by CUT and four Cut Tests under a 550T compression load were successfully completed in December 2008 and January 2009.
Some equipment was then mobilized to Holland for wet testing and WROV familiarisation during February 2009, following which the full equipment spread was mobilised to the Heerema Heavy Lift Vessel "Hermod" in mid March of the same year.
The company introduced a range of technological innovations for this project, including:
- A "castellated" form of cutting through the target to maintain maximum stability of the severed structure prior to the lifting operation.
- Remotely operated wedging system.
- Electronic feedback and monitoring system to supply, in real time, accurate information to the surface CUT Engineer on cutting progress being made. This to allow overall optimization of the cutting procedure.
Cutting Underwater Technologies was formed 10 years ago by Italian parent Tecnospamec. The CUT companies provide the patented Tecnospamec diamond wire cutting systems for clients performing decommissioning, abandonment and other projects in the North Sea and around the globe.
Continued success has seen CUT expand rapidly with operational bases now established in Norway, United States, Singapore and, most recently, Brazil.
CUT UK General Manager Dino Vallarino said, "We developed the concept of a Modular DWCM specifically for the NW HUTTON project with two main objectives in mind:
- To reduce the number of DWCM's required to provide the 60in to 120in cutting range covering the Launch Runner Legs, Inner Legs and Corner Legs of this Platform; and
- With the incorporation of the Castellated Cut, to secure maximum stability of the severed part of the structure. whilst, at the same time, eliminate the need of Guide Rings in the event of having to re-enter a cut
There was a high level of engineering integration and forward-planning and our skilled operators had a detailed plan in place before they went offshore. Every bit of data about every single cut was communicated effectively with those involved in advance to ensure they could move straight from one cut to the next to save as much time as possible.
Vallarino added, "The castellated cutting system we have devised has the potential to offer operators substantial savings. Because the castellated cut leaves a high level of residual stability in the severed structure it may be possible to carry out a number of the major, time-consuming, cuts from a smaller support vessel prior to the arrival on-site of the large, expensive, heavy lift crane barge. Once the crane barge is on site the remainder of the cuts can be executed and the lifting operations carried out.
"We strongly believe that with the now long established level of efficiency, reliability and assured operational performance offered by our Patented Diamond Wire Cutting Systems, further substantial savings could be achieved. The Main Contractors could, for instance, simply decide to reduce the number of different Cutting Services Providers."
CUT offers a standard range of DWCM, ranging from 6in up to 150in, as well as the capability to custom-design, build and test cutting machines to meet any specific client requirements. The machines can be powered and remotely operated from the surface in addition to which they can also operate at any depth with power and positioning being provided by a Workclass ROV. CUT has successfully carried out work to a depth of approx 2,500metres.
The diamond wire technology can cut through any materials including jacket legs, subsea pipelines, flexible lines, multistring conductors, mono-piles and massive anchor chains, efficiently, safely and with negligible or no impact on the environment.
As well as carrying out work for the oil and gas industry both on and off-shore, CUT has successfully entered into the nuclear decommissioning market. Major clients include Acergy, Aker, Allseas, Global Industries, Heerema, Saipem/Sonsub, SBM, Subsea 7, Technip and many others
CUT UK recently moved to new a new HQ facility at Aberdeen Science and Energy Park, comprising 10,000 sq ft of workshops, R&D and test facilities, including a trial and test tank, and 7,000 sq ft of office space over two floors.
The UK company, which has 37 staff, handles CUT's work in Europe to the Caspian Sea, Africa, South & Central America, the Middle East to the Persian Gulf and Mediterranean as well as the North Sea, with the international work accounting for some 60% of its business.