Composite support column assembly for offshore drilling and production

Abstract

An offshore fixed platform support column assembly for deep water hydrocarbon development and production systems comprises an elongated cylindrical composite column which extends upward from a base assembly made up of a central cylindrical reinforced concrete caisson and one or more clusters of cylindrical reinforced concrete storage tanks to a point just below the sea surface. The column is made up of members having wound filament-resin composite cylindrical walls coupled end to end by coupling members which transmit tensile, bending and compressive loads between a platform structure supported at the upper end of the column assembly and the base assembly. The column members may include outer reinforced plastic shells forming buoyancy chambers which are filled with an expanded foam plastic buoyancy material. The column members may include reinforced concrete inner cylinder liners for transferring the static weight of the platform assembly to the seabed through the assembly of the central caisson and the anchor members. In one embodiment the column assembly terminates at its upper end several hundred feet below the surface and is adapted to anchor a submersible vessel by anchor cables which descend through corner support columns of the vessel and are secured to the upper end of the column assembly. The anchor cables may be winched to draw the vessel below the sea surface out of wind and wave action.