A motion compensation system disposed on a structure of a drilling vessel. A stabilization assembly for use with the motion compensation system includes a first arm connectable to the structure, a first sheave connectable to the structure, a second arm connectable to the first arm, and a second sheave connectable to the second arm. At least one of the first arm and the first sheave are connectable to the structure at different locations and the first arm and the second sheave are connectable to the second arm at different locations.

A method for installing an offshore installation is provided, the method including: a) providing a pipe for connecting the offshore installation with another offshore installation or an onshore installation; b) arranging an electrical cable inside the pipe; c) determining a level at or above the seabed, wherein the pipe includes a first portion arranged below the determined level and a second portion arranged above the determined level, and wherein the electrical cable is arranged inside the pipe so as to form a gap with an inner wall of the pipe along the first and second portion; d) determining an amount of cooling liquid such that, when the cooling liquid has a first temperature, the cooling liquid fills the gap along the first portion of the pipe, wherein the second portion of the pipe is free of the cooling liquid, and when the cooling liquid cools the electrical cable.

A platform assembly (10) for providing a work area around a well riser (16) is disclosed. The platform assembly (10) comprises a platform (26) configured to be attached to the well riser (16). The platform assembly (10) further comprises a plurality of tensioning means (28) for supporting the platform (26) relative to a vessel (14) and for supporting the riser (16). At least part of tensioning means (28) is configured to change in length relative to another part of tensioning means (28) responsive to angular motion of the riser (16) and the vessel (14).

A floatable frame structure has concatenated frame modules, each formed of columns arranged substantially vertically. Neighboring columns are interconnected by upper and lower tie bars and form module sections. The connections between the tie bars and columns have rotary joints arranged at upper and lower nodes on the columns. At least one horizontal rotation joint is arranged for each column in the connection to an associated tie bar, and at least one spherical rotary joint or elastic rotary joint is arranged for each tie bar. Each module section is provided with elastic tensile elements secured to diagonally opposite upper and lower nodes, nodes lying diagonally opposite each other in the same horizontal plane and in the same frame module being connected by elastic tensile elements. Some columns form containers with submersible portions with positive buoyancy, and adjacent frame modules sharing at least one column.

A swivel (100) for a mooring line comprises a first element (110) with a first line coupler (111) and a second element (112) with a second line coupler (113). The first element (110) and the second element (112) are rotatable relative to each other. An electric power generator (120) converts a relative rotation between the first element (110) and the second element (112) into electric power. In use, the line couplers (111, 113) are attached to separate segments of the mooring line. A pull F applied to or relieved from the mooring line causes the relative rotation. The swivel preferably contains a battery and a control unit, and may supply power to one or mode sensors, transmitters and/or transducers (130) built into or external to the swivel (100). A system for monitoring a mooring arrangement is also disclosed.

A procedure for moderating the intensity of a hurricane in regions of the seas that are host to the oil and gas industries is described, using the Gulf of Mexico as an example of such a region, and snow-making machines as the instruments for carrying out the procedure. These machines are carried on moving platforms that follow the hurricane and on fixed platforms that are located in the path of the hurricane. In the described procedure snow-making machines are installed on fixed platforms throughout the region, and only those machines that are in the path of an approaching hurricane are turned on, while the snow-making machines on the moving platform(s) are operating continually.

The first aspect of the present invention relates to an offshore drilling system and a method for performing subsea wellbore related activities involving a riser extending between the vessel and a subsea wellbore. The offshore drilling system comprising a drilling vessel with a floating hull, a drilling tower and a tubular string main hoisting device. A vertically mobile working deck with a rig floor slip device is positioned above the moonpool. A telescopic joint and a diverter are provided, wherein the inner barrel of the telescopic joint is secured to the diverter via a flexible joint. Furthermore an integrated heave compensation system is provided such that said travelling block and the mobile working deck move synchronously in heave compensation.

A well intervention semisubmersible vessel and method including a drilling rig further including a non-elevated derrick floor and a handling tower having a single point land out without riser tensioners. The vessel may also include a flush drill floor, a flush moonpool door, a lift frame and personnel access walkway wherein the lift frame is capable of being skidded into position by a skidding system capable of providing personnel access and wherein the skidding system comprises a plurality of skidding rails, at least one remotely operated vehicle, an intervention rising system and storage area, a crane, a moonpool and handling area, a moonpool trolley, at least one fluid pump, and/or at least one tank.

A semi-submersible vessel comprises pontoons having a generally five-sided transverse cross section. In the case of a 4-sided semi-submersible, the columns may be arranged in a generally rectangular form with a column at each corner of the rectangular form, each column having with four sides disposed at a right angle to at least one adjacent side and a fifth side on the exterior of the generally rectangular form disposed at 45 degrees to each adjacent side.

A vessel for e.g. well intervention or deep sea lowering, comprises a moon pool and a hoisting arrangement for lowering and retrieving items, in particular equipment, tools, and/or supplies or modules comprising the same, through the moon pool, into respectively from the sea and onto respectively from the seabed or an installation on the seabed. The vessel further comprises one or more guides for laterally retaining items inside the moon pool, preferably at least two guides positioned on opposite sides of the moon pool.