US 6,935,810 B2 · Semi-submersible multicolumn floating offshore platform

Abstract

A semi-submersible, multicolumn, deep draft, floating offshore oil and gas drilling and production platform comprises a floating hull having an adjustably buoyant base, a plurality of columns vertically upstanding from the base, and an equipment deck that is supported atop the columns when the platform is operationally deployed. Each of the columns comprises a cellular structure that includes a plurality of elongated tubes having a variety of cross-sectional shapes extending from the base to the top of the column. Each of the tubes defines one or more closed compartments. At least one of the compartments has a buoyancy that is fixed, and at least another one of the compartments has a buoyancy that is adjustable. The buoyancy of the compartments and the base can be controllably adjusted with pressurized air to provide a safer and less costly method for deploying the platform for offshore operations.

Claims11

Dependent claims

A hull for an offshore semi-submersible platform, comprising:

a base having an adjustable buoyancy;
and,
a plurality of upstanding columns connected to the base, each column comprising a plurality of elongated, closely-spaced cylindrical tubes connected together by a plurality of vertically elongated webs to form a plurality of non-cylindrical interstitial tubes interspersed with the cylindrical tubes, each of the cylindrical tubes defining a plurality of vertically-arranged, substantially cylindrical compartments, and each of the interstitial tubes defining a plurality of vertically-arranged, non-cylindrical interstitial compartments;
wherein at least one of the cylindrical compartments has a buoyancy that is fixed and at least one of the interstitial compartments has a buoyancy that is adjustable.

1 more element

A method for deploying a floating deep-draft semi-submersible offshore platform, comprising:

providing a hull having an adjustably buoyant base and a plurality of upstanding, adjustably buoyant columns at an inshore water site;
de-ballasting the hull to a shallow draft configuration;
towing the hull in the shallow draft configuration to an intermediate site having deeper water that is shielded from wind and waves;
ballasting the hull such that top ends of the columns extend slightly above the surface of the water;
providing a deck supported by a buoyant deck barge;
transferring the weight of the deck from the barge to the top ends of the columns;
securing the deck to the columns to form the semi-submersible platform;
de-ballasting the hull to an intermediate draft configuration;
towing the platform to an operation site in the intermediate draft configuration;
ballasting the hull to an operational draft configuration;
and,
anchoring the platform at the operational site with a mooring system.

9 more elements

Dependencies are inferred from the claim text.

Semi-submersible multicolumn floating offshore platform

Life of this patent

Semi-submersible multicolumn floating offshore platform

Life of this patent

Abstract

Claims11