Multi-cellular floating platform with central riser buoy
AssigneeDeepwater Technologies, Inc.
InventorEdward E. Horton, III
Life of this patent
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Abstract
A semi-submersible floating platform for offshore drilling and/or production of petroleum product from the seabed includes a base having a first moon pool; a plurality of vertical outer buoyancy columns extending upwardly from the base; a deck structure supported by the buoyancy columns and having a second moon pool; a central columnar buoyancy apparatus having a lower portion guided within the first moon pool and an upper portion guided within the second moon pool; and at least one vertical riser passing through the buoyancy apparatus. Each riser has a lower portion that is horizontally restrained within the buoyancy apparatus below the center of gravity thereof. In a preferred embodiment, the platform includes at least two vertical risers attached to a single buoyancy apparatus.
Claims18
A semi-submersible platform, comprising:
- a base having a first moon pool;
- a plurality of vertical outer buoyancy columns extending upwardly from the base;
- a deck structure supported by the buoyancy columns and having a second moon pool;
- a central columnar buoyancy apparatus that is guided within the first and second moon pools for vertical movement between an upper position and a lower position relative to the base and the deck structure;
- an upper stop assembly on the buoyancy apparatus that is engageable against the deck structure when the buoyancy apparatus is in its upper position;
- a lower stop assembly on the buoyancy apparatus that is engageable against the base when the buoyancy apparatus is in its lower position;
- and
- a riser passing through the buoyancy apparatus and horizontally restrained within the buoyancy apparatus below the center of gravity thereof.
A method of installing a floating, semi-submersible platform at an operational site on the sea surface over the seabed, comprising the steps of:
- (a) providing an assembly comprising a buoyant base having a plurality vertical outer buoyancy columns upwardly therefrom, and a central columnar buoyancy apparatus located centrally within the base, the central columnar buoyancy apparatus being movable vertically relative to the base between an upper position and a lower position;
- (b) towing the assembly at a shallow draft to a first site with the central columnar buoyancy apparatus in its upper position;
- (c) ballasting down the central columnar buoyancy apparatus to its lower position;
- (d) ballasting down the base to a first draft such that the outer buoyancy columns extend just above the sea surface;
- (e) floating a deck structure over the base, the outer buoyancy columns, and the central columnar buoy;
- (f) deballasting the outer columns to lift the deck structure;
- (g) deballasting the central columnar buoyancy apparatus to raise it to its upper position in which it engages the deck structure to form a platform;
- (h) towing the platform to a second site at an intermediate draft;
- (i) ballasting down the platform to an operational draft;
- and
- (j) anchoring the platform to the seabed.
Dependencies are inferred from the claim text.