Abstract: A floating, offshore vessel having surface-piercing columns (e.g., a semi-submersible or a tension leg platform) has means for storage of liquid hydrocarbon liquids inside one or more columns. Hydrocarbon liquids may be stored in only two of the four columns typically found on a semi-submersible, thereby providing a safe-zone where the living quarters are located. A column houses at least one hydrocarbon storage (cargo) tank and at least one variable ballast tank, where the weight capacity of the hydrocarbon cargo tank(s) is approximately equal to the weight capacity of the variable ballast tank(s). The hydrocarbon cargo tank(s) and the variable ballast tank(s) are positioned in such an orientation that the horizontal center of gravity of the cargo tank(s) is (nearly) identical to the horizontal center of gravity of the variable ballast tank(s). Both the hydrocarbon cargo tank and the variable ballast tank may be directly accessible from top-of-column.

Abstract: A floating, offshore vessel having surface-piercing columns (e.g., a semi-submersible or a tension leg platform) has means for storage of liquid hydrocarbon liquids inside one or more columns. There are typically four columns on a semi-submersible. Hydrocarbon liquids may be stored in only two of the four columns, thereby providing a safe-zone where the living quarters are located. A column houses at least one hydrocarbon storage (cargo) tank and at least one variable ballast tank, where the weight capacity of the hydrocarbon cargo tank(s) is approximately equal to the weight capacity of the variable ballast tank(s). The hydrocarbon cargo tank(s) and the variable ballast tank(s) are positioned in such an orientation that the horizontal center of gravity of the cargo tank(s) is (nearly) identical to horizontal center of gravity of the variable ballast tank(s). Both the hydrocarbon cargo tank and the variable ballast tank may be directly accessible from top-of-column.

Abstract: A system comprising a semisubmersible, at least two offloading terminals and shuttle tankers in optional combination with an FSO may be deployed in deep water harsh environments where riser performance (either SCR or LWSCR) is a key performance parameter. The semisubmersible is used to support the risers because of its favorable motion characteristics under harsh conditions. The semisubmersible supports the entire process train and provides well maintenance, which may include water and/or gas injection. The semisubmersible may provide work-over capabilities for well intervention. The produced hydrocarbons are exported through flexible pipes to at least two off-loading buoys. A FSO or shuttle tanker receives the produced hydrocarbons. Two or more off-loading buoys may be employed to allow for uninterrupted production when a shuttle-tanker-only embodiment is utilized.

Abstract: In an offshore production system, a semisubmersible supports the risers and provides the service requirements for the wells, while an associated FPSO provides the processing functions and storage of the produced hydrocarbons. As a result, a greater number of risers can be supported in a harsh environment while the turret and swivel requirements of the system are significantly reduced.

Abstract: A tension leg platform includes a deck supported on the upper ends of three or more columns interconnected at the lower ends thereof by horizontally disposed pontoons. The columns are battered inwardly and upwardly from the pontoons to the deck. Tendons connected at the columns anchor the platform to the seabed. The footprints of the base of the battered columns and the tendons are larger than the footprint of the deck supported on the upper ends of the columns.