Offshore platform with stable configuration on unstable sea-bed - comprising prefabricated submerged infra-structure and emergent superstructure installed separately

摘要

An offshore platform is divided into two basic portions, a submerged supporting infrastructure and an emergent working superstructure carried on the infrastructure after installation of the latter on the sea bed. The infrastructure comprises hollow elements forming caissons capable of ensuring that it floats during its transport to the site. The infrastructure is composed of spaced columns braces so as to constitute the support of the emergent superstructure. The columns rise from a thick base designed to bear on the sea bed by its horizontal lower face after immersion of the infrastructure, exerting a tamping action. The base is integral with anchoring plates projecting downwards to sink deeply into the sea bed and prevent any drift after installation of the infrastructure. These plates are pref. placed in the extension of the columns. The thick base is itself pref. hollow and formed of watertight caissons with independent ballasting allowing controlled ballasting of the infrastructure in the floating state and regulation of its draught. The platform can be put into place correctly in a simpler and more rapidly way than with existing techniques, partic. on sea beds which are movable and unstable, e.g. marly, clayey or muddy beds.