A coiled tubing string may be moved into and/or out from water by deploying an open water coiled tubing control system at sea such as via a vessel. The open water coiled tubing control system comprises a reel configured to accept a coiled tubing string, a surface injector, a reel tensioner configured to control an arch formed by the coiled tubing string between the reel and the surface injector, a controller, a subsea assist jack, and a predetermined set of a predetermined set of sensors. Motion of the surface injector and the subsea assist jack are used in part to move the coiled tubing string accepted by the reel into and/or out of a subsea well by receiving various information at the controller from the predetermined set of sensors and using the controller to resolve the received information to move the coiled tubing string into or out from the subsea well at a predetermined desired speed to achieve an outcome commanded by a single input from an operator.

Systems and methods for pressure communication within a hydro-pneumatic cylinder are provided. The hydro-pneumatic cylinder generally includes a rod, a barrel coaxial to the rod, and a piston assembly disposed within the barrel and connected to the rod. The barrel is hollow to define a chamber, and the piston assembly is axially movable within the chamber to stroke the rod relative to the barrel. The hydro-pneumatic cylinder includes: a flow path formed axially through the rod of the cylinder. This flow path may allow for pressure communication between a low-pressure side of the cylinder and a pressure energized lower pin located at a distal end of the rod. The lower pin may be actuated, via this pressure communication to secure the end of the cylinder to a tension ring on a riser.

A top connection arrangement for a subsea riser comprises a pivot or joint combination disposed between, and fluidly connecting, upper and lower sections of rigid pipe. The pivot combination comprises an upper ball joint about which the upper pipe section is pivotable. A lower joint, being a flexible joint or a tapered stress joint to which the lower pipe section is attached, is fixed to the ball joint in series.

A sleeve is fixed to the ball joint and surrounds the upper pipe section to permit limited pivotal movement of that pipe section about the ball joint. The sleeve may seat into the bellmouth of an I- or J-tube of a surface facility or may be omitted if the lower joint is seated in a hang-off formation.

A locking mechanism is capable of locking the ball joint and hence preventing pivotal movement of the upper pipe section.

Deployment of coiled tubing may be assisted using an apparatus comprising a source of coiled tubing, a coiled tubing distributor that comprises a passageway adapted to allow engaging the coiled tubing from the source of coiled tubing where the passageway comprises a coiled tubing receiver comprising a predetermined radius and a support frame, connected to the passageway, that is adapted to accept a portion of the coiled tubing therethrough, and a slip disposed intermediate the passageway and the support frame where the slip is adapted to accept a portion of the coiled tubing therethrough. The apparatus may be mounted to a structure and a portion of the coiled tubing deployed from the source of coiled tubing about the coiled tubing receiver through the slip. The apparatus is allowed to compensate for motion of the structure while the portion of the coiled tubing is deployed about the coiled tubing receiver through the slip.

A method for mitigating the effects of cable wear in an active heave compensated hoisting system of an offshore vessel in a locked to bottom mode of operation is disclosed. The method comprises supporting an upper end of a string which is connected to a subsea well from a travelling block of the hoisting system, wherein the travelling block is suspended from a crown block via a cable. The method further comprises operating an active heave compensation system to control a drawworks of the hoisting system to pay in and out the cable to compensate for motion of the offshore vessel and maintain a target overpull in the string. The method further comprises adjusting a ballast system of the offshore vessel to vary the draft of the vessel, and controlling the drawworks in accordance with the variation in the draft of the vessel to cause a length of cable to slip through the hoisting system and maintain the target overpull in the string.

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

A compensated elevator link is disclosed. In at least one aspect, the compensated elevator link comprises a plurality of cylinder housings and a rod having a plurality of ends, each end comprising a piston head adapted to be slideably received within one of the cylinder housings for defining first and second hydraulic cylinders. Each hydraulic cylinder has at least one annulus for receiving a non-compressible fluid. The rod comprises a passage for receiving a compressible fluid, wherein each piston head comprises at least one passage to allow selective displacement of the non-compressible fluid between the annulus of the cylinder housing and the passage within the rod during selective displacement of the hydraulic cylinders between a contracted condition to an extended condition for either compression or expansion of the compressible fluid by the non-compressible fluid.

Disclosed herein are embodiments of an offshore drilling rig comprising: a drill floor (107) defining a well center (123); a hoisting system configured to advance a tubular string (128) downwards through the well center (123) and to the seafloor (124) and to apply a lifting force to a tubular string (128) extending through the well center (123) and to the seafloor (124), the lifting force being large enough to support at least a major part of an apparent weight of the tubular string (128); and an anti-recoil system (218) configured to cause, in case of a sudden reduction of a load suspended from the drilling rig, the hoisting system to raise the tubular string (128) while preventing damage to the hoisting system.

A drilling riser cable management system includes a plurality of clamping mechanisms pre-installed on riser joints and a robotic arm. The robotic arm has a cable handling mechanism that is configured to securely install the cable on each clamping mechanism without relying on human manipulation of the cable during installation.