A floating apparatus for use in a casing string and especially for use in offshore casing operations. The apparatus includes a valve configured such that, when there is a pressure differential across the valve below a predetermined mid-pressure threshold, the valve prevents fluid flow and, when the pressure differential exceeds a predetermined high-pressure threshold, said valve non-resiliently allows fluid flow across the valve.

The invention relates to a vessel comprising a moonpool, a firing line hoist system, a stationary main deck for storing equipment and/or tubulars, and a mobile working deck having a front deck section and a rear deck section. The working deck can be moved between a working position and a transporting position. A rear deck lift system is provided for lifting and lowering a rear deck section between the working position and the transporting position. A front deck guide system is provided for guiding a front deck section in a substantially horizontal direction between the working position and the transporting position.

This disclosure includes flow spool riser segment assemblies that are suitable for managed pressure drilling (MPD) and that can be lowered (e.g., when connected to other riser segment assemblies) through a rotary of a drilling rig. Some embodiments are configured to have portions of the flow spool connected (e.g., without welding) below the rotary.

A rotating control device can include a latch assembly with a lock ring that permits displacement of an inner mandrel in one longitudinal direction, and prevents displacement of the inner mandrel in an opposite longitudinal direction. Another rotating control device can include a latch assembly and an equalization valve having an open configuration in which fluid communication is permitted between an exterior and an interior of the rotating control device through the equalization valve, the latch assembly changing from a latched to an unlatched configuration only when the equalization valve is in the open configuration. A method of installing a rotating control device can include releasing a running tool from the rotating control device by producing relative rotation between components of the running tool.

A method transports and installs a heavy subsea structure such as a subsea processing center for produced crude oil or natural gas. The method includes controlledly flooding at least one ballast tank attached to or incorporated into the structure to the extent that the structure becomes negatively buoyant at a pre-determined towing depth. The method also includes towing the negatively-buoyant structure at the towing depth by the Controlled Depth Towing Method (CDTM). After towing to the installation location, the method includes further flooding the ballast tank to lower the structure onto the seabed. At the seabed, a fluid transportation pipe of a subsea production installation may be coupled to pipework of the structure.

Systems and methods for a riser coupling are disclosed. A riser sensor unit for sensing engagement of a riser tool with a riser coupling includes a first sensor attached to a sub of the riser tool. The first sensor is configured to generate a first signal upon detecting contact with the riser coupling, and an intrinsic safety barrier is configured to transmit the first signal to a control system.

A mechanical lockdown system for a subsea wellhead connector includes a lockdown member or plate that engages with a tie rod that is connected to the wellhead assembly. The lockdown system includes a support member that is permanently secured to an annular ring through which the tie rod passes. The lockdown system also includes a first handle and a second handle that are installed using a plunger or spring loaded system such that mechanical lockdown system can be easily moved from a lockdown open position to a lockdown engaged position as and when desired with minimal ROV interface.

Extender jumper systems and methods including an extender jumper system having an extender jumper assembly with a flowline and first and second connectors positioned at first and second ends of the flowline, and a support assembly configured to couple the extender jumper assembly to a support structure within a subsea field and to support the second connector to facilitate attachment between the second connector and a corresponding connector of another extender jumper or a jumper.

A method of lowering an apparatus (1) through a body of water comprising lowering a guiding element (25) and a weight (27) through the body of water, the lower end of the guiding (element 25) being attached to the weight (27) such that the guiding element (25) is under tension and is maintained in a generally vertical orientation when in its lowered position, and lowering the apparatus (1) through the body of water whilst being guided by the guiding element.

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).