Offshore installation varies with the type of development involved. Fixed platforms have the most work involved; jackets and topside decks need to be transported to the well location. Once the jacket is in its final position and piled, the deck is lifted into position and welded to the jacket. Following the installation, the hook-up is completed to services and production lines on the jacket. Any additional modules are lifted into position, fixed and hooked-up to the deck unit, before the platform is commissioned.
Pioneering Spirit’s primary area of focus is the installation and removal of large steel jacket-based platforms in hostile areas such as the North Sea. In particular, Pioneering Spirit will target the topsides and jackets that cannot currently be lifted in a single section by crane barges. The primary aim is for topsides heavier than 10,000 t and jackets higher than 70 m, although smaller platforms can be accommodated equally well.
Pioneering Spirit is able to install large topsides in a single lift. When installing topsides in a single lift, the amount of structural steel can be reduced and offshore hook-up activities are minimised as units can be transported offshore in very large sections; entire platform topsides, up to a weight of 48,000 t, can be installed in one piece, pre-fabricated onshore. This can lead to significant field development cost savings.
In March 2015 Statoil awarded Allseas a contract for the installation of three large platform topsides on the Johan Sverdrup field in the Central North Sea. Pioneering Spirit will install the topsides – with weights varying from 17,000 t to 23,000 t – for the drilling, processing and living quarter platforms in 2018 and 2019.
When installing large jackets, conventionally they need to be cut up into small sections suitable for crane lifts, requiring lengthy and complex subsea cutting operations. Pioneering Spirit will be able to remove jackets weighing up to 25,000 t in a single lift, thereby limiting subsea work and associated risks.