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Juliet & Minke Decommissioning Project - Completed November 2019

Utility ROV Services (URS) prove their worth after successful completion of a subsea decommissioning work scope on Neptune Energy E&P UK’s Juliet and Minke fields.

URS was set up in 2013, to react to the MER UK decommissioning cost and safety challenge, by developing and commercialising specialist subsea technology originating from the salvage industry. URS are successfully disrupting the cost base and delivering significant improvements, with proofs of low cycle times. The full benefits of the technology are brought to bear, when combined with cost effective vessel platforms and innovative contracting strategies.

URS provided their highly innovative suite of decommissioning tooling, based on their market leading load bearing multitool platform known as the UTROV (Utility ROV).

Juliet and Minke activities included de-burial of subsea infrastructure, recovery of concrete mattresses, cutting and recovery of pipeline, spools & flexibles, clearance of debris and burial of exposed pipeline ends. The project combined a dual crane construction vessel, Work class ROV and the UTROV system. The result was a highly adaptable and capable decommissioning spread.

“URS were a game-changer on this project. Neptune Energy required a productive CSV spread which could cope with unforeseen scenarios offshore ensuring the project would be executed safely and within budget. The ability for the onboard project team to call-off tooling as unanticipated complications presented themselves eliminated the risk of additional transits and un-scheduled port calls. This meant that the CSV could leave each site completely clear with no requirement for unbudgeted follow-on scopes.” David Hunt (Neptune Energy Subsea Project Manager)

URS mobilised six different tools all positioned, monitored and powered from the UTROV. Each tool could be called upon as required to react to the unpredictability of the decommissioning campaign. The system utilises minimal deck space and can be managed by a seven-man multi-disciplined team.

The following tooling range was mobilised; Mattress Recovery Tool, Clamshell Grab, Controlled Flow Excavator, Tine Grab, Shear Cutter and Pipe Grab. Access to these tools kept the CSV nimble and adaptable allowing it to change between the UTROV tooling as dictated by the program, the weather and the unforeseen.

Cycle times for each operation at Juliet & Minke:

  • Fastest mattress recovery – 6 minutes deck to deck
  •  Average mattress recovery cycle time – 24 minutes deck to deck
  •  Average cycle time per cut & move – 8 minutes (moving 10m to next cut)
  •  Average cycle time per pipe relocation to subsea basket – 15 minutes (moving 20m to basket)
  •  Average cycle time per poor integrity mattress relocation to basket – 25 minutes

The above cycle times are derived from a representative volume of data gathered from accurately recorded times on URS dive logs.

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