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Title: Caisson shield for arctic offshore production platform

Abstract

A caisson shield for the protection of an offshore production platform and, more particularly, a caisson shield for use in an arctic environment for the protection of the offshore structure in iceberg-infested waters which is capable of absorbing the destructive forces of an impact produced by a large iceberg. The caisson shield consists of an essentially annular concrete structure encircling at least the submerged support section of the offshore production platform including vertically upstanding concentrically spaced, annular side walls, a horizontal slab base resting on the marine bottom on which the side walls are supported, and a slab top supported on the side walls, and including annularly spaced internal radial partition walls whereby the entire overall caisson shield structure provides a generally toroidal configuration incorporating a plurality of closed compartments. In one embodiment of the invention, located along the outer annular wall is a plurality of arcuate wall sections forming a series of arches and enclosed compartments between each arcuate wall section and the outer annular wall, which impart a ''scallop-like'' configuration to the outer circumference of the caisson shield. The ''scallop-like'' outer walls are capable of resisting and absorbing extremely high ice loads by being adapted to progressively crushmore » the leading edge of an impacting iceberg and to thereby minimize the crush of the iceberg against the caisson shield before coming to rest against the shield.« less

Inventors:
;
Publication Date:
OSTI Identifier:
5338393
Patent Number(s):
US 4504172
Assignee:
Mobil Oil Co. EDB-85-145682
Resource Type:
Patent
Resource Relation:
Patent File Date: Filed date 11 Jul 1983; Other Information: PAT-APPL-512803
Country of Publication:
United States
Language:
English
Subject:
02 PETROLEUM; 03 NATURAL GAS; OFFSHORE PLATFORMS; SHIELDING; SHIELDS; IMPACT STRENGTH; ARCTIC REGIONS; ICEBERGS; ICE; MECHANICAL PROPERTIES; POLAR REGIONS; 020300* - Petroleum- Drilling & Production; 030300 - Natural Gas- Drilling, Production, & Processing

Citation Formats

Clinton, J. D., and Reusswig, G. H. Caisson shield for arctic offshore production platform. United States: N. p., 1985. Web.
Clinton, J. D., & Reusswig, G. H. Caisson shield for arctic offshore production platform. United States.
Clinton, J. D., and Reusswig, G. H. Tue . "Caisson shield for arctic offshore production platform". United States. doi:.
@article{osti_5338393,
title = {Caisson shield for arctic offshore production platform},
author = {Clinton, J. D. and Reusswig, G. H.},
abstractNote = {A caisson shield for the protection of an offshore production platform and, more particularly, a caisson shield for use in an arctic environment for the protection of the offshore structure in iceberg-infested waters which is capable of absorbing the destructive forces of an impact produced by a large iceberg. The caisson shield consists of an essentially annular concrete structure encircling at least the submerged support section of the offshore production platform including vertically upstanding concentrically spaced, annular side walls, a horizontal slab base resting on the marine bottom on which the side walls are supported, and a slab top supported on the side walls, and including annularly spaced internal radial partition walls whereby the entire overall caisson shield structure provides a generally toroidal configuration incorporating a plurality of closed compartments. In one embodiment of the invention, located along the outer annular wall is a plurality of arcuate wall sections forming a series of arches and enclosed compartments between each arcuate wall section and the outer annular wall, which impart a ''scallop-like'' configuration to the outer circumference of the caisson shield. The ''scallop-like'' outer walls are capable of resisting and absorbing extremely high ice loads by being adapted to progressively crush the leading edge of an impacting iceberg and to thereby minimize the crush of the iceberg against the caisson shield before coming to rest against the shield.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Mar 12 00:00:00 EST 1985},
month = {Tue Mar 12 00:00:00 EST 1985}
}
  • An offshore structure is disclosed for use in drilling and producing wells in arctic regions having a conical shaped lower portion that extends above the surface of the water and a cylindrical upper section. The conical portion is provided with a controlled stiffness outer surface for withstanding the loads produced by ice striking the structure. The stiffness properties of the outer shell and flexible members are designed to distribute the load and avoid high local loads on the inner parts of the structure.
  • An offshore platform structure, particularly intended to be installed in waters where drifting iceberg frequently appear, the platform structure being intended to be founded in a sea bed and comprises a substructure, a superstructure rigidly affixed to the substructure and extending vertically up above the sea level supporting a deck superstructure at its upper end. The horizontal cross-sectional area of the substructure is substantially greater than tath of the superstructure. The substructure rigidly supports a fender structure, the fender structure comprising an outer peripherally arranged wall and an inner cylindrical wall the inner and outer wall being rigidly interconnected bymore » means of a plurality of vertical and/or horizontal partition walls, dividing the fender structure into a plurality of cells or compartlents. The fender structure is arranged in spaced relation with respect to the superstructure.« less
  • The invention relates to an offshore platform operable for use in arctic locations where prolonged ice conditions may be encountered. The platform includes a lower barge hull having an exterior configuration in the general shape of a rectangular frustum and being operable to be fixed relative to a desired seabed site. The lateral side walls of the barge hull are heated for facilitating movement of contiguous sea ice upwardly relative to the barge side walls to fail the ice in bending as it advances toward the barge hull. A deck is positioned above the lower barge hull and is supportedmore » by a first and second column at an elevation whereby the lower surface of the deck will be above and out of contact with sea ice passing over the hull. The deck is positioned relative to the barge hull in a posture such that at least a portion of the deck extends beyond an imaginary vertical plane projecting upwardly from at least one longitudinal edge of the upper surface of the barge hull.« less
  • A mobile drilling and production platform for arctic regions is described in which a hull having a deck forming the production platform is supported on a first set of parallel runners secured to the underside of the hull and extending fore and aft with spaces between the runners. A second set of parallel segmented runners are secured to the underside of the hull and extend perpendicular to the first set of runners, the second set of runners including plurality of sections positioned in the spaces between the first set of runners. A plurality of rotating ice cutters are mounted onmore » the hull and extend down in front of the ends of each of the runners, the ice cutters cutting channels in the ice in which the runners move and support the hull. One set of runners is vertically movable from the hull relative to the other set of runners whereby the weight of the hull can be transferred from one set of runners to the other to permit movement of the platform along two perpendicular axes or coordinance of motion.« less
  • An offshore well drilling and/or production operation which is carried out on top of a layer of ice which extends over unfrozen water. A ring of thermal insulation is formed on top of the ice around the area of the drilling and/or production operation so that the ice thickness under the ring is thinner than the ice adjacent the ring thereby forming an annular depression in the underside of the ice. The depression will capture and hold any hydrocarbons or other fugitive materials that may escape under the ice in the area of the drilling and/or production operation.