A downhole apparatus comprises a casing string with a removable plug therein to block flow therethrough. A flow barrier is positioned in the casing below the removable plug and the removable plug and the flow barrier defining a buoyancy chamber therebetween. A debris barrier positioned above the removable plug includes a frangible disk. A stretchable connecting ring is connected to the frangible disk and to the casing.

A downhole apparatus comprises a casing string with a removable plug therein to block flow therethrough. A flow barrier is positioned in the casing below the removable plug and the removable plug and the flow barrier defining a buoyancy chamber therebetween. A debris barrier positioned above the removable plug includes a frangible disk. A stretchable connecting ring is connected to the frangible disk and to the casing.

A downhole apparatus comprises a casing string with a removable plug therein to block flow therethrough. A flow barrier is positioned in the casing below the removable plug and the removable plug and the flow barrier defining a buoyancy chamber therebetween. A debris barrier positioned above the removable plug includes a frangible disk. A stretchable connecting ring is connected to the frangible disk and to the casing.

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.

Method for quantifying a volumetric flow rate of a flow of drilling mud in a floating structure for subsoil drilling, said method comprising: providing a flowmeter (50) on a floating structure (20) for subsoil drilling, said flowmeter (50) being configured for generating a flow signal (FS); providing a detection device (70) on said floating structure (20), suitable for generating a heave signal (HS) representative of a substantially vertical heave of said floating structure (20); acquiring said flow signal (FS) and said heave signal (HS) through a processor (60); activating said processor (60) in order to transform said flow signal (FS), thereby obtaining a corresponding first spectrum (S1) in the frequency domain; activating said processor (60) in order to transform said heave signal (HS), thereby obtaining a corresponding second spectrum (S2) in the frequency domain; activating said processor (60) in order to compare said first spectrum (S1) with said second spectrum (S2), thereby obtaining a resultant spectrum (RS); activating said processor (60) in order to transform said resultant spectrum (RS), thereby obtaining a corresponding resultant signal (SX) in the time domain; activating said processor (60) in order to: determine a mean value of said flow signal (FS), add said resultant signal (SX) to said mean value, thereby obtaining a quantification of a flow of drilling mud in said floating structure; activating said processor (60) in order to generate an output signal (OUT) representative of said quantification.

A system on a marine vessel or platform supports a load while allowing heave compensation. The load is supported via a hydraulic actuator. A transformer of the system includes a power source and at least one hydraulic pump/motor, for communicating energy between any two of: the hydraulic actuator; a hydraulic accumulator; and a power source. A valve associated with the pump/motor is switchable during at least one cycle of the pump/motor for selectively providing fluid communication between a drive chamber of the pump/motor and any of the hydraulic actuator, the hydraulic accumulator, and a hydraulic fluid reservoir, via at least one port of the drive chamber, so as to allow a desired displacement of hydraulic fluid from the pump/motor to be obtained.

An offshore subsea wellbore activities system and method wherein use is made of a tower and a motion arm assembly with vertical drive adapted to move the motion arm along a vertical motion arm rail relative to the tower. Also use is made of a wellbore activities device comprising a riser tension frame having an upper frame section, a lower frame section provided with a riser attachment device adapted to attach a riser to said lower frame section so as to extend in a firing line, and a vertical riser load bearing structure, e.g. formed by struts. The wellbore activities device further comprises a coiled tubing injector, a wireline lubricator, and one or more pressure control devices associated with the coiled tubing injector and/or the wireline lubricator received by and individually movable within the riser tension frame. The wellbore activities device provides a lateral firing line access passage allowing to transfer an elongated wellbore tool or a wellbore tubular in vertical orientation thereof by means of the motion arm assembly in a substantially lateral motion between and a remote position outside of the riser tension frame and an operative position within the riser tension frame and aligned with the firing line.

An offshore subsea wellbore activities system and method wherein use is made of a tower and a motion arm assembly with vertical drive adapted to move the motion arm along a vertical motion arm rail relative to the tower. Also use is made of a wellbore activities device comprising a riser tension frame having an upper frame section, a lower frame section provided with a riser attachment device adapted to attach a riser to said lower frame section so as to extend in a firing line, and a vertical riser load bearing structure, e.g. formed by struts. The wellbore activities device further comprises a coiled tubing injector, a wireline lubricator, and one or more pressure control devices associated with the coiled tubing injector and/or the wireline lubricator received by and individually movable within the riser tension frame. The wellbore activities device provides a lateral firing line access passage allowing to transfer an elongated wellbore tool or a wellbore tubular in vertical orientation thereof by means of the motion arm assembly in a substantially lateral motion between and a remote position outside of the riser tension frame and an operative position within the riser tension frame and aligned with the firing line.

A compensating rig elevator is provided to eliminate set-down weight from threaded connectors during make-up of a pipe stand and thereby provide an ability to reduce the risk of thread galling and cross-threading. The elevator may comprise one or more hoist assemblies with bail arms that deflect as the compensating rig elevator is suspended by the bail arms and a tubular is placed in the compensating rig elevator. The bail arms actuate a locking mechanism to secure the compensating rig elevator in a closed position around the tubular. The compensating rig elevator can also have compensating rams and a slip system to positively engage the tubular and bear the weight of multiple tubulars.

A compensating rig elevator is provided to eliminate set-down weight from threaded connectors during make-up of a pipe stand and thereby provide an ability to reduce the risk of thread galling and cross-threading. The elevator may comprise one or more hoist assemblies with bail arms that deflect as the compensating rig elevator is suspended by the bail arms and a tubular is placed in the compensating rig elevator. The bail arms actuate a locking mechanism to secure the compensating rig elevator in a closed position around the tubular. The compensating rig elevator can also have compensating rams and a slip system to positively engage the tubular and bear the weight of multiple tubulars.