Offshore arctic structure

An offshore structure adapted for use in a body of water having a surface and a floor and having ice sheets floating on the surface, said structure comprising:

• a base;
• sloped walls, each having an upper end and a lower end, attached to the base at the lower end and sloping upwardly and inwardly;
• and
• a substantially horizontal top portion capable of supporting the ice sheets and having a substantially smooth and unobstructed surface attached to the top ends of the sloped walls, the top portion located at or near the surface of the body of water so that the floating ice sheets are deflected by the sloped walls onto the top portion and flex and ride over the structure and return to the water surface substantially intact.

An offshore structure adapted for use in a body of water having a surface and a floor and having ice sheets floating on the surface, said structure comprising:

• a base located on the floor of the body of water;
• means for attaching the base to the floor;
• an upper section which is frustum shaped and has a substantially horizontal top portion capable of supporting the ice sheets, the top portion having a substantially smooth and unobstructed surface, the upper section attached to the base so that the top portion is located at or near the surface of the body of water so as to allow encroaching ice sheets to flex and ride over the structure and return to the surface of the body of water substantially intact;
• a work platform located in the structure and below the surface of the body of water;
• and
• a plurality of ballasting compartments disposed in the structure.

An offshore structure adapted for use in a body of water having a surface and a floor and having ice sheets floating on the surface, said structure comprising:

• a base;
• means for attaching the base to the floor;
• sloped walls, each having an upper end and a lower end, attached to the base at the lower end and sloping upwardly and inwardly;
• inlets supported within the sloped walls permitting the intake of water from the body of water;
• means for pumping the intake water from the inlets through a pipeline to shore, the pumping means supported on the base;
• a plurality of ballasting compartments attached to and located about the periphery of the base;
• and
• a substantially horizontal top portion capable of supporting the ice sheets attached to the top ends of the sloped walls and located at or near the surface of the body of water, the top portion having substantially smooth and unobstructed surface so that the floating ice sheets are deflected by the sloped walls onto the top portion, ride over the structure, and redurn to the water surface.

In an offshore structure located in a body of water having ice sheets floating on its surface, a method for reducing the loads imposed on said offshore structure by the movement of said ice sheets, said method comprising the steps of:

• providing said offshore structure with a generally frustum shaped upper section capable of deflecting said floating ice sheets upwardly and capable of supporting said ice sheets;
• positioning said offshore structure in said body of water so that the top of said frustum shaped upper section is located at or near the surface of said body of water;
• and
• permitting said floating ice sheets to deflect upwardly, ride over said offshore structure and return to the surface of the water substantially intact.