Abstract: Apparatus for the connection and/or disconnection of a marine riser to a floating vessel comprising, in a main embodiment, a plurality of connecting lines. The, lower ends of these connecting lines are attached to the riser and are arranged to be moveable between a first helical configuration which allows connection, via a turret, between the riser and the floating vessel and a second helical configuration wherein said connecting line is disconnected and. retracted from said floating vessel. A method of installing said connecting lines is also disclosed.

Abstract: The invention provides a marine riser apparatus (1) for use in the production of hydrocarbons from offshore wells and an associated method of installation of the apparatus at sea. The riser tower comprises rigid pipelines arranged in a riser tower bundle (2) and extending from a wellhead on the seabed (4) to a point below the sea surface where they are connected to flexible jumpers (3) which extend from the tower structure to connect the tower structure to a surface vessel or platform (5). The riser apparatus further comprises a buoyancy device (7) attached to the riser tower bundle, such that the buoyancy device is located above and exerts a buoyancy force on the riser tower, the buoyancy module also supporting an intermediate section of at least one of the jumpers.

Abstract: The relative position and orientation between two subsea structures (210, 212) are measured by ultra-short baseline acoustic metrology. Dual mode master/slave (220, 222) stations comprising a multi-transducer array are fitted in known position and orientation relative to each structure. The first station (220) is operated in master mode to determine the position and direction of the second structure (222) relative to the first (220). The second station (222) is operated in master mode to determine the position and direction data from both operations the apparatus calculates relative position and orientation between the structures. The dual mode stations can be replaced by a master station and a slave station, swapping places.

Abstract: There is provided method and apparatus for buoyancy distribution along a substantially vertical submarine structure (100), in which the structure is provided with multiple modules (110), slidably mounted to the structure such that when vertically deployed at sea the modules are free to adjust their positions up or down the structure by sliding, the force of each module acting upon the module above it rather than locally along the structure, resulting in the cumulative force (460) from the modules acting substantially against the top of the structure. Forces between modules may be evenly distributed by use of compliant intermediaries (310).

Abstract: There is disclosed improved mooring apparatus and method suitable for use with large offshore vessels. To avoid deploying an anchor with a full weight of mooring chain, they are deployed separately. An anchor, such as a suction anchor (1), is fitted with a short chain (C1) with one end permanently connected (6) thereto and its free end temporarily placed in a chain locator (8), which is positioned so as to be accessible after deployment of the anchor to the seabed, minimising the potential for seabed material to cause disruption. The anchor with its short chain is deployed to the seabed and at some stage the free end of a mooring chain (C2) is lowered to and accurately guided (100) into the chain locator, such that both free ends align. A pin (101) is inserted by an ROV to interconnect the two chains, after which the combined mooring chain (C) is tensioned, withdrawing it from the chain locator.