A petroleum drilling, production, storage and offloading vessel having a hull, a main deck, an upper cylindrical side section extending downwardly from the main deck, an upper frustoconical side section, a cylindrical neck section, a lower ellipsoidal section that extends from the cylindrical neck section, and a fin-shaped appendage secured to a lower and an outer portion of the exterior of a bottom surface. The upper frustoconical side section located below the upper cylindrical side section and maintained to be above a water line for a transport depth and partially below the water line for an operational depth of the petroleum drilling, production, storage and offloading vessel.

A first permissible operating range of the self-elevating vessel is determined based on a first structural analysis of the self-elevating vessel under a first set of conditions. A structural utilization ratio of the self-elevating vessel is determined based on a second structural analysis of the self-elevating vessel under first and second sets of conditions. Safety of lowering the self-elevating vessel from an elevated state to a first hull draft level is determined when the structural utilization ratio is less than a predetermined value. Safety of lowering the self-elevating vessel from the first hull draft level to a second hull draft level is indicated when positional displacement data obtained while the vessel is at the first hull draft level indicates that the positional displacement of the self-elevating vessel while at the first hull draft level is within the first permissible operating range.

A continuous vertical tubular handling and hoisting buoyant structure has a hull, a main deck, an upper neck extending downwardly from the main deck, an upper frustoconical side section, an intermediate neck, a lower neck that extends from the intermediate neck, an ellipsoidal keel and a fin-shaped appendage secured to a lower and an outer portion of the exterior of the ellipsoid keel. The upper frustoconical side section is located below the upper neck and maintained to be above a water line for a transport depth and partially below the water line for an operational depth of the buoyant structure. An automated stand building system mounted to the hull is in communication with a controller and configured to make up the marine risers, make up casing, and make up drill pipe.

A buoyant structure with a hull, a main deck, a lower inwardly-tapering frustoconical side section; a lower generally rounded section extending from the lower inwardly-tapering frustoconical side section; a generally rounded keel; a fin-shaped appendage secured to a lower and an outer portion of the hull proximate the generally rounded keel. In embodiments, the keel has a first frame extending from the keel and a first keel extension connected to the first frame.

A buoyant structure has a hull having a main deck. The hull further contains a lower inwardly-tapering frustoconical side section that extends from the main deck, a lower generally rounded section extending from the lower inwardly-tapering frustoconical side section, a generally rounded keel, and a fin-shaped appendage secured to a lower and an outer portion of the exterior of the hull proximate the generally rounded keel, the fin shaped appendage having a shape selected from the group consisting of: a triangular shape, a hump shape and a pair of connected triangular projections shape.

A buoyant structure contains a hull. The hull has a main deck, a lower inwardly-tapering frustoconical side section that extends from the main deck, a lower generally rounded section extending from the lower inwardly-tapering frustoconical side section, a generally rounded keel, a fin-shaped appendage secured to a lower and an outer portion of an exterior of the keel, and an offloading device slidably connected to an outside surface of the hull configured for rotating around an outer circumference of the hull.

A buoyant structure contains a hull having a main deck, a lower inwardly-tapering frustoconical side section that extends from the main deck, a lower ellipsoidal section extending from the lower inwardly-tapering frustroconical side section, a keel having an n-polytope shape, a fin-shaped appendage secured to a lower and an outer portion of the exterior of the keel having the n-polytope shape, and a plurality of columns connected between the keel having the n-polytope shape and the main deck forming one or more tunnels between the plurality of columns.

A system for marine electricity generation and solid carbon production includes an offshore marine platform on which is mounted a regassification system for regassification of liquid methane; a methane splitting system producing solid carbon and gaseous hydrogen; and a power generation system producing electricity and exhaust heat. A first marine vessel is moored adjacent the marine platform for delivery of the liquid methane, and a second marine vessel is moored adjacent the marine platform for removal of the solid carbon produced by the methane splitting system. The hydrogen produced from the methane splitting system is used in a fuel stream for the power generation system. The exhaust heat from the power generation system is utilized in the methane splitting process. Also mounted on the marine platform is a solid carbon handling system disposed to manage the large amount of solid carbon resulting from the methane splitting process.

A potable water producing system for disposition at a salt water body and methods of producing potable water are provided. The system includes a wave energy conversion system (AWECS) and a portable filtration system. The AWECS forms a floating articulated barge having an onboard desalination system including reverse osmosis membranes. The filtration system is a sand filter residing on a damping plate submerged in the salt water body and filters the adjacent salt water for providing filtered salt water to the onboard desalination system. Wave action on the articulated barge provides energy to pump and pressurize the filtered salt water from the sand filter to the reverse osmosis membranes to produce potable water. The wave action on the articulated barge effects shaking of the reverse osmosis membranes, thereby rendering them self-cleaning. The potable water can be used for various applications, e.g., bottling, replenishing aquifers, ground and/or aquifer remediation, irrigation, etc.

This floating liquefied-gas production facility (1) is equipped with: a gas turbine unit (20); a liquefaction facility (90) that has a primary refrigeration compressor (40) driven by the gas turbine unit (20), and cools natural gas; a drum-circulation-type exhaust heat recovery boiler (30) that recovers the energy of exhaust heat from the gas turbine unit (20) as steam; a component separation system (85) that uses the steam generated by the drum-circulation-type exhaust heat recovery boiler (30) as a heat source to separate components in natural gas obtained from the ocean floor, and sends said components to the liquefaction facility (90); and a fuel gas supply device (100) that compresses end-flash gas and/or boil-off gas, and supplies said compressed gas to the gas turbine unit (20) as fuel.