Marine oil rig with separate submerged substructure - has superstructure floated over and attached via axially displacing legs

摘要

The marine or aquatic installation may be used in the exploitation of maritime oil-fields and has separately fabricated substructural and super-structural elements. The substructure transmits loads to the sea-bed, and is totally immersed in the sea whilst the super structure once installed, locates above sea-level. the superstructure can be floated into position over the substructure, either by towing or self-propulsion, and in prepn. for coupling to the substructure. A transition structure, provides for a demountable coupling and connection of the super-structure to the substructure, and the super-structure to the substructure, and the super-structure mountings, permit relative vertical displacement between the super-structure and the transition-structure. The facility for relative vertical displacement can be used to compensate natural forces during lifting and erection. The transition structure may comprise a series of vertical columns, which can be displaced axially relative to the sub-structure.