초록 ▼

A gravity-type offshore structure, useful as an offshore drilling platform, e.g., is provided for use in ice-covered waters such as offshore of the Alaskan and Canadian North Slope. The structure is composed of a plurality of floatable and controllably ballastable modules, each of which can be fully

A gravity-type offshore structure, useful as an offshore drilling platform, e.g., is provided for use in ice-covered waters such as offshore of the Alaskan and Canadian North Slope. The structure is composed of a plurality of floatable and controllably ballastable modules, each of which can be fully submerged. The modules are stackable by selective ballasting and deballasting operations in a suitable sequence to define a mobile offshore structure. The structure is assemblable adjacent a site of use and is floatable after assembly to, from and between successive sites of use. At each site of use the assembled structure is ballasted by sea water to be supported by the sea floor and to have sufficient deadweight, in combination with its support by the sea floor, to stand against ice loads urging the structure laterally of the site. Major ones of the modules preferably are constructed of reinforced concrete arranged within the modules in a honeycomb cellular fashion. A reinforced concrete armor belt is removably installed around the structure at its on-site load waterline. The structure is useful in a range of water depths. The armor belt is mountable to the structure at a number of different elevations on the structure to suit differing on-site load waterline locations. Individual modules can be used with other modules of the same or different size in a series of offshore structures individually useful in a characteristic range of water depths.

대표청구항 ▼

An arctic offshore structure of the gravity type movable buoyantly to and from a position over a site of use located on a sea floor under waters in a selected range of depths, the structure when installed at the site extending from a lower end substantially at the sea floor through and above the wat

An arctic offshore structure of the gravity type movable buoyantly to and from a position over a site of use located on a sea floor under waters in a selected range of depths, the structure when installed at the site extending from a lower end substantially at the sea floor through and above the water surface to an upper operations end of the structure which is adapted to carry a selected operations facility, the structure through a portion thereof between (a) a first location adjacent its lower end and below the water surface and (b) a second location in the structure a substantial distance above the water surface having substantially vertical and substantially flat outer walls, the structure in said portion being comprised of at least one unitary base unit, each base unit being floatable, each base unit being reversibly ballastable adequately to impart to the structure sufficient negative buoyancy, in combination with the nature of the sea floor, to maintain a desired position at the site under environmental forces applied horizontally to the structure.