The present invention provides a buoyant system and method for a hydrocarbon offshore floating platform to be coupled and decoupled from a subsea buoyant extension with risers slidably coupled thereto. The buoyant system can allow rigid risers to be coupled and decoupled and alternatively move between a first elevation below the offshore floating platform, such as at the buoyant extension, and a higher second elevation at the offshore floating platform independent of a spool piece, arch support, and flexible joint for the risers. The buoyant system can reduce riser stress by reducing bending required for the riser to form a catenary or other curved shape even as a rigid riser.

Embodiments disclosed herein describe cylindrical structures with indents configured to reduce vortex induced vibrations (VIV). For example, the cylindrical structures may be configured to reduce VIV for drilling risers subject to ocean currents. In embodiments, the indents may be positioned on an outer surface of the cylindrical structures, wherein the indents may be parallel pairs. The pairs may be mirrored between a first end and a second end of the cylindrical structure, and be positioned in a helical pattern, which may be continuous or staggered.

The present invention relates to a marine drilling riser joint, adapted for the securement of one or more umbilicals (36) thereto. The marine drilling riser joint comprises one or more umbilical gutter assemblies (8), connected to or formed integral in an outer surface of a buoyancy module on the exterior of the marine drilling riser joint and provided parallel to the riser pipe, the umbilical gutter assembly comprising: an umbilical gutter (8) adapted to accommodate one or more umbilicals; and a resilient gutter cover (82a, 82b), which is elastically deformable by a loom tool, which resilient gutter cover in a closed position covers the umbilical gutter and in an elastically deformed position provides a working clearance to allow the one or more umbilicals to be introduced into the umbilical gutter.

A float includes a body portion having a first side surface and a second side surface, an inner surface and an outer surface, the first and second side surfaces being generally planar and forming an acute angle therebetween, the inner and outer surfaces being non-planar, and the body portion configured such that when positioned laterally adjacent an inverted second float and vertically adjacent a third float, the first side surface of the float abuts a surface of the inverted second float, and the inner surface of the float engages an outer surface of the third float.

Methods and systems are described for monitoring the integrity of a subsea pipeline network to transport the production fluid from a subsurface wellhead to surface facilities. More specifically, the described methods and systems are for monitoring the integrity of a riser pipe network and can include installing one or more inclinometers to the buoyancy tank and/or vertical riser structures.

A method of monitoring variation in the thrust exerted by at least one buoy exerting traction on an undersea pipe, wherein: 1) the deformation of at least one optical fiber is measured by measuring variation of an optical signal in said fiber extending on the surface or embedded securely in the bulk of at least one of the following support elements: a) the buoy; b) at least a portion of: b1) the length of the tubular wall of the pipe or b2) an anticorrosion coating or a thermally insulating material fastened on the surface of said pipe, on which said buoy exerts traction, and c) an abutment part secured to said pipe or buoy, and on which said buoy exerts said thrust; 2) a variation of said thrust exerted by said buoy is determined as a function of said variation of the optical signal.

An installation of bottom-to-surface connections of at least two undersea pipes (11-1, 11-2) resting on the sea bottom (10), and a rigid pipe (1-1, 1-2) constituted by a vertical riser having its bottom end (1a) fastened to a base (9-1, 9-2) at the sea bottom (10), and having its top end (1b) tensioned by an immersed float (4-1, 4-2); and a flexible connection pipe (2-1, 2-2) providing the connection between a common floating support (12) and the top end (1b) of the vertical riser via a junction device (3-1, 3-2; wherein two hybrid towers are connected together by at least one rigid separator bar (5) having a length not less than the diameter of the larger-diameter float.

A flexible elongate element for installation in a body of water to extend between a seabed connection device and a unit arranged at the opposite end of the flexible elongate element. At least one lateral displacement device is connected to a portion of the flexible elongate element and configured to displace at least a portion of the flexible elongate element a lateral distance away from a first axis extending between the seabed connection device and the unit, the at least one lateral displacement device including a spring member. The flexible elongate element may be a flexible riser, umbilical, hose, or cable.

A vortex-induced vibration (VIV) suppression apparatus including a base member having an interior surface dimensioned to at least partly encircle a tubular member; a fin protruding outward from an exterior surface of the base member; and at least one aperture formed through the base member, from the interior surface to the exterior surface.

A marine installation system for installing an item on a riser includes a cable extending between two supporting points, the cable being inclined relative to the horizontal; a first ROV arranged to mount the item on the cable at a first position; and a second ROV arranged to remove the item from the cable at a second position, and to install the item on the riser.