Jacket removal – cut and lift query

  • Jacket removal – cut and lift query

  • Colin Hopkins

    Organizer
    September 18, 2019 at 3:24 pm

    Hi folks, I have a query. Looking at a jacket removal (derogation candidate) and sits in water depth of about 138.4m. Total jacket weight 16,000tn, with a potential derogates jacket removal of 10,000tn . Looking to verify if an HLV can cut and lift in a single lift with a 10,000tn jacket and approx 117m in height. Think it can be achieved by the heavy lifters based on a single lift and walk in to inshore location  for further cutting / removal to shore, however unsure with hook height etc.  
    Appreciate if anyone from the Decom community could assist, looking to save valuable time in obtaining info. Thanks for your help. 

  • David Leake

    Member
    September 18, 2019 at 5:21 pm

    Colin,

    Technically feasible to lift and transport in one piece but pretty much a certainty that nearshore setdown and further cutting required in order to lift any part of the Substructure onto a quayside.

  • Colin Hopkins

    Organizer
    September 18, 2019 at 5:59 pm

    Thanks for the response Dave. I’m assuming the water depth was sufficient e.g. Stord Norway and executed in a similar manner as the Miller jacket. However, was unsure whether the hook-height of Thailf, S7000 or Sliefner was such that this could be done in one lift (single trip) or multiple lifts (two trips). We have conducted similar removal assessments on other assets jackets but though this jacket might pose a challenge. If water depth was an issue at onshore location, we would also assume working at a ‘suitable’ inshore location and conducting a barge transfer. The prize is minimising offshore vessel time and if it could be done in a single trip, that’s where the value can be created. 

    • David Leake

      Member
      September 18, 2019 at 9:35 pm

      Colin,

      Absolutely agree on minimising offshore time as being the prize but hook height is always going to be a limiting factor with the current vessels in the marketplace – its a challenge to be able to have sufficient clearance to land on a quayside with a single lift. Hence unfortunately its a grounding pad or multiple cuts.

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