US 8,807,062 B2Granted

Unconditionally stable floating offshore platform

AssigneeHorton Wison Deepwater, Inc.

InventorsArcandra Tahar, Edward E. Horton, III, James V. Maher

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Abstract

A platform for offshore drilling and/or production operations comprises an equipment deck. In addition, the platform comprises a buoyant hull coupled to the equipment deck and configured to extend below the surface of the water. The hull comprises a first column having a central axis, an upper end coupled to the deck, a lower end distal the deck, and a plurality of axially stacked cells between the upper end and the lower end. Each cell defining an inner chamber within the cell and an exterior region outside the cell. The plurality of cells includes a first cell extending from the upper end of the first sub-column and a second cell axially positioned below the first cell. The first cell is water-tight. Further, the second cell includes a gas port configured to supply a buoyancy control gas to the inner chamber of the second cell.

Claims7

Dependent claims

A method for designing an offshore platform, the method comprising:

(a) setting an initial value for each of a plurality of parameters that affect the stability of the offshore platform;
(b) setting an upper limit and a lower limit for each of the plurality of parameters, wherein the upper and the lower limit for each parameter defines a range for each parameter;
(c) varying a first of the plurality of parameters after (a) and (b);
(d) determining, by a computer, a first plurality of righting moments of the offshore platform for each of a first plurality of increasing heeling angles during (c), wherein the heeling angles result from a heeling moment produced by a constant 100 knot wind;
(e) determining, by the computer, whether each of the first plurality of righting moments is greater than zero for each of the first plurality of heeling angles that are non-zero during (d);
(f) determining, by the computer, whether the first plurality of righting moments increase in value after decreasing in value during (d);
(g) selecting, by the computer, values for the first plurality of parameters for which the first plurality of righting moments has an increasing set of values following a decreasing set of values through progressively increasing heeling angles;
and
(h) assigning, as a preferred design value for the offshore platform, a value for each of the first plurality of parameters for which the righting moments has the increasing set of values through the progressively increasing heeling angles.

6 more elements

Dependencies are inferred from the claim text.