A structural block is fabricated with necessary components and structure for LNG storage and/or process. The structural block may be an LNG tank with the same configuration as that in an LNG carrier. The structural block may also be a regasification plant or a liquefaction plant to be used for LNG process. An existing vessel, e.g. an LNG carrier, is cut apart to form a forward section and an aft section. The forward section and the aft section are moved away from each other to form a space therebetween. The structural block is then placed into the space and jointed to the forward and aft sections, by welding for example, to form an integrated new vessel. The structural block provides the new vessel with increased LNG storage and transportation capabilities as well as regasification and/or liquefaction process facilities to meet the increased demand for LNG storage, transportation and processing.

A floating hydrocarbon processing/storage structure with a first and second assembly, each including a hull having side walls, one or more storage tanks and a deck structure, a connection structure interconnecting the hulls, processing equipment situated on the deck structures, at least one riser connected to a subsea hydrocarbon well and to the processing equipment and/or storage tanks, with a mooring system connecting the processing/storage structure to the sea bed, each hull including a hull deck structure bridging the side walls, the connection structure including a central deck extending at or near the height of the hull deck structures along at least 70% of the length of the hulls, the central deck supporting at least one of: risers vertically extending from the central deck between the hulls to the sea bed, fluid ducts horizontally supported on the central deck, and at least one drilling/work-over rig or crane.

A floating hydrocarbon processing/storage structure with a first and second assembly, each including a hull having side walls, one or more storage tanks and a deck structure, a connection structure interconnecting the hulls, processing equipment situated on the deck structures, at least one riser connected to a subsea hydrocarbon well and to the processing equipment and/or storage tanks, with a mooring system connecting the processing/storage structure to the sea bed, each hull including a hull deck structure bridging the side walls, the connection structure including a central deck extending at or near the height of the hull deck structures along at least 70% of the length of the hulls, the central deck supporting at least one of: risers vertically extending from the central deck between the hulls to the sea bed, fluid ducts horizontally supported on the central deck, and at least one drilling/work-over rig or crane.

A floating hydrocarbon processing/storage structure with a first and second assembly, each including a hull having side walls, one or more storage tanks and a deck structure, a connection structure interconnecting the hulls, processing equipment situated on the deck structures, at least one riser connected to a subsea hydrocarbon well and to the processing equipment and/or storage tanks, with a mooring system connecting the processing/storage structure to the sea bed, each hull including a hull deck structure bridging the side walls, the connection structure including a central deck extending at or near the height of the hull deck structures along at least 70% of the length of the hulls, the central deck supporting at least one of: risers vertically extending from the central deck between the hulls to the sea bed, fluid ducts horizontally supported on the central deck, and at least one drilling/work-over rig or crane.

Described is a multi-use offshore structure having a first configuration and a second configuration. The first configuration includes a pontoon base disposed at a lower end of the multi-use offshore structure. A deck is disposed at an upper end of the multi-use offshore structure, and hull column structures extend between the pontoon base and the deck. The second configuration includes the pontoon base, the deck, and the hull column structures of the first configuration. A set of sponsons is formed to be installed on the hull column structures, and a deck expansion unit is connectable with the deck.