Abstract: Aspects of the present disclosure relate generally to apparatus for semi-submersibles, including hulls of semi-submersibles. In one implementation, a hull for a semi-submersible includes a pontoon having one or more sides, and a plurality of columns extending upwards from the pontoon and configured to support a topsides. Each one of the plurality of columns has a cross section that is in a plane perpendicular to an axial centerline of the respective one of the plurality of columns. The cross section includes a first portion being rectangular in shape and a second portion being triangular in shape and having an apex that extends inboard from the first portion.

Abstract: A semi-submersible structure with buoyant vertical columns and a buoyant pontoon. Unlike the typical semi-submersible where the pontoons are attached directly between the columns, the pontoon of the invention encircles the columns and is arranged outside of the columns. The pontoon encircling the columns simplifies construction and attachment of the pontoon and columns and improves the heave characteristics of the structure.

Abstract: A spar hull centerwell arrangement wherein an adjustable buoyancy centerwell device (ABCD) is disposed within the centerwell of the structure. The adjustable buoyancy centerwell device is rigidly connected to the interior walls of the hard tank and defines an adjustable buoyancy centerwell device within the centerwell. The adjustable variable buoyancy unit is a water and airtight buoyancy chamber that allows the interior ballast to be changed as required. This device can also be used as a storage unit for on board fluids and other produced hydrocarbons.

Abstract: A semi-submersible structure with buoyant vertical columns and a buoyant pontoon. Unlike the typical semi-submersible where the pontoons are attached directly between the columns, the pontoon of the invention encircles the columns and is arranged outside of the columns. The pontoon encircling the columns simplifies construction and attachment of the pontoon and columns and improves the heave characteristics of the structure.

Abstract: A floating spar hull for offshore oil and natural gas exploration and production having a centerwell arrangement wherein a supporting wellbay deck is positioned in the centerwell at a level below the uppermost portion of the spar hull in the centerwell. The wellbay deck is attached to the spar hull by any suitable means such as shear plates such that a space remains between the deck and the spar hull for risers. This allows equipment to be placed below the uppermost deck of the topsides and eliminates or minimizes wind loads on the equipment.

Abstract: A riser disconnect and support mechanism for flexible risers and umbilicals on an offshore structure with low under keel clearance. A main body portion includes an inverted and truncated conical or convex section substantially at the center of the main body portion. The main body portion and conical section receive risers therethrough by means of a plurality of conduits through the main body portion and conical section. A plurality of projections extend radially outward from the main body portion. A plurality of arch-shaped riser supports are provided on each projection to support risers and/or umbilical lines and control their bending radii. The projections extend out from the main body portion at a distance that allows the portions of the risers below the main body portion to hang at an angle and bend radius in accordance with the design tolerances of the risers to prevent buckling or damage due to excessive bending while keeping the risers from contacting the sea floor.