Case Study

Dunlin Conductor Removal: QuikDeck®

Fairfield Energy
Fixed Platform in the North Sea

The Dunlin Alpha platform was installed in 1977, comprising a concrete gravity base structure (CGBS), supporting a steel topsides deck and production facilities.

Dunlin Alpha ceased production mid-2015 and planning and execution for the decommissioning of the installation was completed over the following years with the topside finally removed in early 2022. To facilitate the eventual removal of the topside, a programme for removing the majority of the 44 conductors was required. These conductors were removed in parallel with the final P&A campaign.

Key Summary
  • Provision of underdeck access system to provide long term temporary access to conductors
  • Installation of 50t of underdeck support steelwork
  • Onshore trials for proof of concept for underdeck cutting of conductors
  • Destruct and removal of a range of clamps, braces and bridles for conductors
  • Destruct and removal of underdeck steelwork and piping
  • Management of specialist cutting vendor
  • Planning and execution of a high volume of complex lifts
  • Compilation or workpacks and provision of project management team for assigned workscopes
The Challenges

As part of the preparation for topside removal, our client required us to remove the conductors utilsing the topside drilling package. In order to pull the conductors through the narrow openings in the conductor bay, all appurtenances were required to be removed from the conductors from an underdeck location.

Underdeck access to all conductors would be required in order to remove a series of grouted clamps and braces located at various heights in the splashzone. The underdeck structure of the platform had a wide flat bottom area with no established means of access in place, which could not be accessed by traditional scaffolding systems.

Grouted clamps would need to be cut and safely removed from conductor, then cross hauled out from underdeck meaning a high volume of complex lifts in an exposed underdeck location.

Simultaneous inboard / outboard workscopes would be required to be executed productively to meet the intended project schedule.

The Solution

AquaTerra proposed our Quikdeck suspended access system, which was initially trialled on a smaller scope. To complete the workscope a 1200m2 Multi –tiered QuikDeck access system, designed, supplied and installed by AquaTerra. The Quikdeck system was complemented by netting systems to provide full encapsulation when working at height. A catenary wire system was also used to access the underdeck walkways for destruct.

Onshore construction-led structural engineering support was provided to support project planning and execution for all destruct workscopes.

Working with our clients nominated engineering contractor a Test Frame was fabricated for onshore trial cutting of conductors to prove the concept for removing grouted clamps from the Quikdeck.

Multi discipline team all trained in QuikDeck so no requirement for crew changes between installing the Quikdeck system and executing complex cutting, lifting and destruct workscopes.

Key project personnel from AquaTerra were embedded within the clients project team to ensure early engagement.

AquaTerra personnel installing on Quikdeck on Dunlin AlphaThree AquaTerra personnel using AquaTerra's QuikDeck suspended working platform to remove conductors on the Dunlin Alpha decommissioning project
The Result

The innovative use of the QuikDeck system allowed client and non-rope access specialist vendors unlimited access to underdeck areas that were never previously accessible. Rapid QuikDeck installation, destruct and modification times resulted in approx. 75% time saving over traditional scaffolding.

90% of underdeck destruct operations completed in board resulted in minimal reliance on standby vessel and maximized productivity.

All workscopes executed by multi-discipline workforce to minimise bed space and flights and maximise productivity.

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