Heave suppressed offshore drilling and production platform and method of installation

摘要

A heave suppressed, floating offshore drilling and production platform comprises vertical columns, lateral trusses connecting adjacent columns, a deep-submerged horizontal plate supported from the bottom of the columns by vertical truss legs, and a topside deck supported by the columns. The lateral trusses connect adjacent columns near their lower end to enchance the structural intergrity of the platform. During the launch of the platform and towing in relatively shallow water, the truss legs are stowed in shafts within each column, and the plate is carried just below the lower ends of the columns. After the platform has been floated to the deep water drilling and production site, the truss legs are lowered from the column shafts to lower the plate to a deep draft for reducing the effect of wave forces and to provide heave and vertical motion resistance to the platform. Water in the column shafts is then removed for buoyantly lifting the platform so that the deck is at the desired elevation above the water surface.