Ambient Lifter trial showcases capability to revolutionise decommissioning heavy lifts
The estimated cost of decommissioning North Sea platforms and subsea structures on the UKCS is in the region of £51 billion (as reported by the Oil & Gas Authority in 2019). Innovative technology such as Ambient Lifter, facilitates the removal and transportation of subsea structures, and is potentially the key to unlocking cost-effective solutions for decommissioning offshore subsea structures.
NZTC supported the development and field trial of an alternative subsea heavy lift device. The Ambient Lifter system can be used to lift, lower or manoeuvre any subsea object by controlling buoyancy and ballast in low pressure pipes. This new way of lifting subsea assets provides a faster and more cost-effective lifting solution, providing a new methodology to subsea lifting challenges.
The innovative technology developed during this project was a metal-framed coil of stiff plastic pipe, proportionately filled with air and water, separated by a specialist gel pig to give neutral buoyancy subsea. This created the “Ambient Lifter”, which can be connected to a heavy subsea piece of equipment and remove it to surface. When water is pumped out of the device the Ambient Lifter gets lighter until it achieves neutral buoyancy. It can then lift and manoeuvre the equipment using the propulsion thrusters on the attached work class ROV.
The use of this technology will help drive significant cost savings for both subsea installation and decommissioning applications.
This new way of lifting subsea assets provides a faster and more cost-effective solution for subsea lifting challenges. The use of this technology will help drive significant cost savings for both subsea installation and decommissioning applications.
The subsea trial conducted at Buckie harbour, in Aberdeenshire, demonstrated deploying the Ambient Lifter subsea using an ROV was fully controllable, thus allowing a certified 10 tonne clump weight to be picked up off the seabed and moved around the harbour solely by means of an ROV.
During the trials at Fraserburgh Drydock, a repeat of the 10-tonne clump weight lift along with an additional trial to test a single Ambient Lift with the integrated subsea tooling to simulate a subsea operation. The subsea tooling was also manoeuvred around the drydock by an ROV.
Following the successful subsea trial, the priority for Ambient Lifter system is to secure its first commercially funded application. In addition, a number of technology developments will be considered for further development on the system during its lifecycle:
- Custom-designed software package to increase controllability of the Ambient Lifter through the ROV
- Reducing the frame weight in turn increases the lift capacity of the same volume of pipe. The team are currently designing an Ambient version that has only a lightweight steel ring integrated with polyester webbing
- Development of the ROV interface to make the Ambient Lifter more compatible with a wider range of WROVs
- A diver-friendly Ambient Lifter with the option for the ballast to be controlled subsea by the diver, or topside from the vessel
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