Techniques and systems to reduce deflection of a riser extending from an offshore platform. A device may include a main tube disposed along a length of the device. The device may also include a support member that may be coupled to the main tube, wherein the support member may surround the main tube. The device may include a buoyancy assembly that may at least partially surround the main tube, wherein the buoyancy assembly may have an elongated non-circular and non-cylindrical shape. The buoyancy assembly may also include buoyancy foam.

An apparatus including an external surface portion shaped so as to mate with a docking device, and two half-shells having internal surfaces of semi-circular cross section. The apparatus further includes a plurality of segments arranged inside the two half-shells and including teeth for gripping onto a shaft, and an installation tool operable to cause the two half-shells to close around the shaft, thereby securing the apparatus to the shaft.

Current profile of water (e.g., ocean) around a riser connected to a wellhead may be measured and used to determine integrated current load on the riser at any given moment in time. The integrated current load may be used to estimate the wellhead fatigue damage rate at that moment in time. The estimated wellhead fatigue damage rate may be used to make operational decisions for the well.

A buoy accomplishes a fluid connection between a vessel on a water surface and a subsea template located on a seabed via at least one riser. A fluid is transported by the fluid connection from the vessel to the subsea template, and the fluid is injected from the subsea template (120) into a subterranean void via a drill hole. At least one valve in the buoy is controllable from an external site in response to commands so as to shut off the fluid connection from the vessel to the at least one riser.

A subsea fluid storage system comprises: a seabed foundation; a tensile member such as a pipe or a wire extending upwardly from the foundation; and a subsea buoy applying buoyant upthrust to support the tensile member in an upright orientation. At least one fluid storage container is disposed between the foundation and the buoy. The or each container may be disposed around the tensile member, for example with the tensile member extending through the container. The container has at least one inlet or outlet for fluid communication with a source or a consumer of fluid to be stored in the container.

A method for assembling a riser from a platform on the surface of a body of water includes assembling segments of riser end to end through a drill floor using a main drilling unit on the platform. At least one auxiliary line is assembled from segments connected end to end through an auxiliary hoisting unit on the platform. The auxiliary hoisting unit is displaced laterally from the main drilling unit. The assembled riser is connected to a wellhead proximate the bottom of the body of water.

The invention involves utilizing variable reluctance measurement technology (VRMT) sensors to monitor forces and stresses on drilling risers and riser towers. The tension monitoring system described herein includes an optimized configuration of variable reluctance measurement technology sensors, wherein the sensors have increased wire turns around each end of their C-cores or alternatively are mounted on mechanical amplifiers or both. An array of optimized variable reluctance measurement technology sensors can be configured at multiple points on a riser system. The VRMT sensors may be integrally attached to the risers or flexible joints for the risers, or may be installed on existing riser or flexible joint systems.

A drilling riser system includes a plurality of interchangeable dockable modules having sealable hydraulic connections configured to connect to a module docking structure disposed in at least one specific segment of a drilling riser and to seal the hydraulic connections. Each of the interchangeable dockable modules includes at least one of an hydraulic termination or connection to an hydraulic device for each of a fluid conduit in fluid communication with the and at least one auxiliary line associated with the riser.

The invention relates to a buoyancy module (100, 200, 300, 400, 500, 700) which comprises multiple buoyancy elements (104, 204, 304, 404, 504, 604, 704) coupled to one another. Each of the buoyancy elements has a recess (110, 210) and the buoyancy elements are laterally juxtaposed with their recesses aligned with one another to encircle the elongate member in use. Multiple buoyancy elements are stacked one upon another along a direction which is axial with respect to the elongate member in use, to form a buoyancy module of a predetermined axial depth. The recesses of the buoyancy modules together form an axially extending passage through which the elongate member passes.

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 risers subject to ocean currents.