A vessel adapted to perform subsea wellbore related operations involving a riser string that is assembled from releasably interconnected riser sections and extends between a subsea wellbore and the vessel. The riser string vertical handling system of the vessel includes a controlled motion device that is adapted to displace the riser string lifting tool in at least one horizontal direction relative to the riser spider device at least whilst travelling between the elevated and lowered position thereof loaded by the riser string suspended from the riser string lifting tool, thereby allowing to establish an inclined travel path with selectively variable inclination of the riser string lifting tool relative to an imaginary vertical line through the riser string passage of the riser spider device, e.g. said inclined travel path having an inclination selected to correspond to an actual water current induced inclination of an upper portion of the riser string during the riser string assembly process.

A sandglass type ocean engineering floating structure is provided with an upper structural body shaped as a circular truncated cone or frustum and a lower structural body shaped as a regular circular truncated cone or regular frustum; under a combined state, the smaller bottom surface of the upper structural body is fixedly connected with the smaller bottom surface of the lower structural body to form a junction surface; the axis of the upper structural body and the axis of the lower structural body are positioned on the same straight line; the larger bottom of the upper structural body acts as an upper deck of the floating structure and the larger bottom of the lower structural body acts as a lower plate underwater of the floating structure; the junction surface is a full-load waterplane of the floating structure.

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.

The present invention relates to a marine structure comprising a launch and recovery system for a submersible vehicle, and methods of operating the marine structure. The system comprises: a docking receiver, a towing head comprising a locking mechanism and being connectable to the docking receiver (13), a towing arrangement adapted to mechanically connect the towing head to the marine structure and being adapted to control the distance between the towing head and the docking receiver, and a lifting device connected to the docking receiver and being adapted to move the docking receiver relative to the marine structure. The lifting device can arrange the docking receiver in a towing head receiving and/or releasing position in which the docking receiver: (i) is completely submerged into the body of water, and (ii) is prevented from moving relative to the marine structure.

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.

Embodiments relate generally to a turret system for use in an FPSO vessel. The turret system may comprise a turret body and windlass subsystem. The turret system may comprise a top and bottom surface, first and second mooring line storage sections, and first and second mooring line channel sections. Each mooring line storage section may include an opening and cavity. Each opening is operable to receive a mooring line. Each mooring line channel section may be an elongated passageway for a mooring line to pass between an exterior of the FPSO vessel and a mooring line storage section. The windlass subsystem may comprise a rotatable member, and configured to be transportable between a plurality of locations. When the windlass assembly is configured to be secured to the turret body, the windlass assembly is configurable to control a movement of a mooring line.

A moon pool control device (5) for a marine vessel (1) comprises one or more closure members (8a,b) arranged for movement in the moon pool, between a moon pool closing position in a region of the moon pool opening (7), a moon pool open position, and a retracted position, and guiding means (14a,b; 15a,b; 17a,b; 18a,b) and motive means (9a,b; 10a,b; 22) configured for moving the closure member between said positions. In a particular embodiment, a pair of closure members (8a,b) and corresponding guiding means (14a,b; 15a,b; 17a,b; 18a,b) and motive means (9a,b; 10a,b; 22) are arranged on opposite lateral sides of the moon pool and configured to cooperate to close the opening (7) when both closure member s are in the closing position. The closure members comprise a continuous surface that forms a fluid barrier. The closure members may be retrieved onto the deck of the vessel.

A vessel and method to perform subsea wellbore related operations, e.g. slim hole technique drilling of a subsea wellbore are disclosed. The vessel has a hull with at least one moonpool defining first and second moonpool areas. A vertical tower is mounted on a tower supporting hull structure and has a vertical operative face. A hoisting device has a winch and winch driven cable, and is adapted to suspend a load from said vertical tower via said at least one winch driven cable and to manipulate the suspended load in a firing line of the tower that extends along and outside of said vertical operative face of the tower. The tower is slewable about a vertical slew axis by means of a slewing drive at least into first and second operative positions wherein the firing line extends through the first and second moonpool areas respectively.

A semi-submersible drilling vessel has a deckbox structure and a shaker room. A downward sloping mud return line is provided that passes mud from the diverter to the shaker room. In the shaker room there are one or more shale shaker devices, one or more upstream mud tanks arranged to receive gas cut mud from the one or more shale shaker devices, and a vacuum degasser having an inlet pipe extending into an upstream mud tank, a vacuum tank, a vacuum pump, and an outlet, and a degassed mud tank receiving degassed mud from the outlet of the vacuum degasser. The degassed mud tank has an effective height between the bottom thereof to the operational mud level in said degassed mud tank that is greater than the corresponding effective height of said one or more upstream mud tanks. The degassed mud tank is mounted so that—in operation—the operational mud level in said degassed mud tank is at least 1.5 meter, preferably at least 2 meters, higher than in said one or more upstream tanks with the vacuum degassers self-suction effect causing the mud to be pumped from the upstream tank, via the vacuum degasser, into the degassed mud tank.

A method of lowering a discrete load (32) from a pipelay yessel comprises: holding a rigid rod (30) on an upright launch axis where the rod extends through a hold-back system (26); coupling a lower end of the rod to the load; connecting a wire (24) to the load either directly or indirectly via the rod; operating the hold-back system to advance the rod downwardly, hence submerging the load, while the weight of the load is suspended from the holdback system via the rod; when the load is underwater and beneath the splash zone, transferring the weight of the load directly or indirectly from the holdback system to the wire; and continuing to lower the load in the water, suspended directly or indirectly from the wire. The method may be reversed to recover a load from a subsea location, such as when lifting a wellhead or blowout preventer from the seabed.