Abstract: A system for improving the static and dynamic stability of an offshore floating structure in which outriggers having a unit with an inertial mass are supported from the structure to hold each unit at a radial distance from a centre of rotation of the offshore floating structure and be entirely submerged. Water may enter and exit a tank in a unit to statically adjust and dynamically control stability and dampen roll and pitch of the structure. The outriggers can be raised for tow. The outriggers ballast can be adjusted during tow, installation and in operation. The units can transport mooring lines. An embodiment of a hydrocarbon production or support facility is described with the dynamic flexible risers connected to a support structure of the system.

Abstract: A method for installing a subsea structure at a target installation site in an underwater location is disclosed. The method includes connecting at least one mooring line and at least one leading line to the structure, and towing the structure via the leading line from a deployment position to the target installation site, such that the structure moves both vertically and horizontally between the deployment position and the target installation site. The mooring line is anchored, e.g. to an anchoring device on the seabed, and can incorporate a ballast to apply a sinking force to the structure in proportion to the length of unsupported line. The mooring line and the leading line can together stabilise the structure as it descends to the installation site. The non-vertical installation allows accurate structure placement, e.g. in crowded fields, with less sensitivity to tidal or current forces.

Abstract: A buoy comprising a hydrocarbon processing facility for processing production fluids received from an offshore well, the facility being disposed in a portion of the buoy that is submerged below the waterline, has a pressure relief channel for venting gas above the waterline. The pressure relief channel is in fluid communication with a chamber in the buoy which may contain the processing facility, or other equipment presenting an explosive hazard, and is the only conduit through which high pressure is exhausted. In particular, the pressure relief channel can contain the effects of an over-pressurisation event within the chamber such as ignition of flammable gas, and mitigate structural damage to the buoy.

Abstract: A subsea fluids storage facility comprises a tank for holding and separating fluids which is equipped with ballast capacity and a separable base to be deployed upon the seabed in shallow or deep water, and the storage facility is connectable to a surface production facility, especially a buoy for processing fluids. In deep water the tank is held at a depth above the base for temperature controlled stabilization of produced oil in the tank.

Abstract: A subsea fluids storage facility comprises a tank for holding and separating fluids which is equipped with ballast capacity and a separable base to be deployed upon the seabed in shallow or deep water, and the storage facility is connectable to a surface production facility, especially a buoy for processing fluids. In deep water the tank is held at a depth above the base for temperature controlled stabilization of produced oil in the tank.

Abstract: A subsea fluids storage facility comprises a tank (11) for holding and separating fluids which is equipped with ballast capacity (14) and a separable base (12) to be deployed upon the seabed in shallow or deep water, and the storage facility is connectable to a surface production facility, especially a buoy (24) for processing fluids. In deep water the tank (11) is held at a depth above the base (12) for temperature controlled stabilization of produced oil in the tank (11).

Abstract: A subsea fluids storage facility comprises a tank (11) for holding and separating fluids which is equipped with ballast capacity (14) and a separable base (12) to be deployed upon the seabed in shallow or deep water, and the storage facility is connectable to a surface production facility, especially a buoy (24) for processing fluids. In deep water the tank (11) is held at a depth above the base (12) for temperature controlled stabilisation of produced oil in the tank (11).