DOF Subsea has completed the recovery of rigid pipeline as part of a decommissioning project in the UK North Sea using an MDL back-deck spread.
The 4” rigid pipe was retrieved from water depths of c. 115m using an MDL 2-track tensioner on board the Skandi Skansen. MDL also provided a dedicated angled grillage for efficient sea-fastening during moblisation and demobilisation and to aid in the height requirements for the shear cutter used to cut lengths of pipe.
In total 12km of product was retrieved, including Water Injection, Gas Lift and Production Pipelines. Once on deck, the product was cut into 13m sections for efficient disposal onshore.
The TTS-2/140 Series Tensioner met the operational requirements for a 20-tonne line pull, alongside a pivoting top track to enable product positioning.
The system’s top track can be hinged open/closed to facilitate the loading or unloading of the product without compromising deck space, thanks to its compact footprint.
Additionally, the Failsafe Grip System, inherent in all MDL tensioners, ensures the unit maintains constant grip on the product, even in the case of critical failure or power loss.
MDL also provided optional entry and exit rollers for this scope to further facilitate efficient handling of the product into the firing line for cutting on board.
David Stott, MDL Project Engineer, said:
“This was a great project to be involved with, supporting the client’s decommissioning programme.
“Understandably, retrieval of redundant infrastructure is a cost-driven operation, but it still needs to be carried out safely and professionally to minimise environmental hazards.
“Our tensioner fleet sets the rental market standard for pipe lay and retrieval safety, and our 25Te 2-track tensioner offered efficiencies that helped the client execute this scope ahead of schedule.
“This latest project adds to the tensioner’s varied track record which – among many flex-lay scopes - also includes replacement of rigid pipeline in an environmentally-protected area in the US West Coast and installation of a 25mm fibre optic cable offshore Mexico – all demonstrating that this is a safe and convenient solution for oil and gas and renewable scopes alike.”