A motion compensating system is usable on a vessel during well intervention operations through a riser. The system includes a first floor; a second floor; a plurality of hydraulic cylinders connecting the first floor to the second floor; a bearing retainer attachable to the second floor; a spherical bearing provided between the second floor and the bearing retainer, wherein the spherical bearing includes a central opening therethrough for the riser to allow angular movement of the riser relative to the first and second floors; an insert bearing sleeve at least partially located inside the central opening of the spherical bearing; and a slip bowl attachable to the insert bearing sleeve. Each of the first floor, the second floor, the bearing retainer, the insert bearing sleeve and the slip bowl have an opening therethrough for the riser, and each opening is aligned with the central opening of the spherical bearing.

The present invention concerns a connection system 1 for a marine drilling riser 10 having one or more auxiliary lines 20, the connection system comprising: a moveable coupling member 30 having at least one first connector and at least one second connector coupled to the at least one first connector, wherein the at least one second connector is adapted for engaging with at least one connector of an auxiliary line of the marine drilling riser The connection system further comprising a control line support 18 for fixing at or adjacent an outer surface of the marine drilling riser; a control line supported by the control line support and for attachment to the moveable coupling member; and a tailing line for attachment to the moveable coupling member.

A sheave assembly for use in a handling system or tensioning system, the sheave assembly having one or more sheaves arranged about a shaft and cone sub-assembly. The shaft and cone sub-assembly may include one or more pairs of bearing cones configured to interface with a plurality of bearing rollers to facilitate rotation of the one or more sheaves about the shaft and cone sub-assembly. The shaft and cone sub-assembly may be configured to be arranged in a fixed rotational position during handling or tensioning operations. The shaft and cone sub-assembly may further be configured to be rotated or repositioned about a central, longitudinal axis of the sub-assembly. The shaft and cone sub-assembly may be configured to rotate independent of the sheave(s) so as to reposition the one or more pairs of cones with respect to applied loading on the sheave assembly from the handling or tensioning operations.

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 composes 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.

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.

A hoisting system for a drilling rig, which has a crown block for attaching to a derrick, the crown block comprising a plurality of sheaves; a travelling block suspended from the crown block via a hoisting cable, the travelling block comprising a plurality of sheaves and being connectable with a payload, the travelling block being arranged to move along a workpath; the hoisting system further comprising: a floating block comprising a plurality of sheaves reeved on the hoisting cable; wherein the floating block is configured to move between: a first arrangement in which the floating block is fixed relative to the crown block; and a second arrangement in which the floating block is fixed relative to the travelling block; wherein the hoisting system is arranged such that, when the floating block is in one of the first or second arrangement, the sheaves of the floating block overlap a sheave of the crown block or travelling block in a direction of the workpath.

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.

A passive heave compensator, including an elastic cable, an electromagnetic damping device, a cylindrical sector, and a disc damping plate. The electromagnetic damping device includes a first cylinder including a helical coil, a permanent magnet mechanism disposed in the first cylinder, a first cover plate, a second cover plate, a first sliding shaft, a second sliding shaft, a first spring, a second spring, a first end cover, and a second end cover. The cylindrical sector includes a roof plate, a middle plate, a base plate, a first side plate, a second side plate, and a curved plate. The disc damping plate is disposed around the middle plate of cylindrical sector. The elastic cable is directly connected to the electromagnetic damping device. The electromagnetic damping device is disposed in the central part of the cylindrical sector. The middle plate is disposed between the roof plate and the base plate.

Embodiments of a top-mounted hoisting system include a single-layer winch drum located at an uppermost end of a derrick or drilling mast, a drill string handling tool, and one or more drill lines extending from the single layer winch drum to the drill string handling tool. The drill string handling tool may be a top drive. When the drill line is connected directly to the lifted load, the drill line experiences far less load cycles than when the line runs through crown and travelling blocks. If the drum diameter is large enough, cut-and-slip operations may be eliminated, and the drill line may be replaced at longer time intervals. Embodiments provide for lower weight and may provide lower cost as a result. The top-mounted drum does not take up any space on the drill floor and less total length of drill line is also required than if the drum was floor-mounted.

A connector system and method, of which the connector system includes a first conduit having a lower coupling and a first alignment feature, and a frame configured to be coupled to an oilfield tubular, and configured to receive the first conduit and a second conduit. The frame includes a second alignment feature configured to mate with the first alignment feature such that the lower coupling is aligned with the second conduit, and the first alignment feature is configured to slide vertically with respect to the second alignment feature such that the lower coupling is brought into engagement with the second conduit while the first and second alignment features are mated together.