A subsea flexible riser installation has a seabed foundation and a steep-configuration flexible riser anchored to the seabed by the foundation. An attachment formation is fixed relative to the riser and a locating formation is fixed relative to the foundation, both at positions elevated above the seabed. The locating formation is engaged with the attachment formation on the riser. This holds the attachment formation and the riser against movement when engaged, protecting the base of the riser from over-bending and fatigue.

A method and apparatus are disclosed for determining a bending radius of a flexible pipe. The apparatus includes at least one bend sensor element comprising an elongate flexible substrate and at least one bend sensitive element on the substrate that has at least one electrical characteristic that is responsive to angular displacement of the substrate. The apparatus also comprises a flexible crush resistant elongate housing that supports and surrounds the bend sensor element.

A riser top connector assembly (20) is shown. The assembly (20) includes a first connector part (21) arranged on a flexible jumper prepared for connection with a second connector part (40) arranged on top of a marine riser tower assembly projecting from the seabed. The first connector part (21) is provided with suspension means adapted to engage with supporting means in order to be supported and be able to tilt in the marine riser tower assembly. The first connector part (21) includes a housing (22) that receives an extendable termination hub (23) having a clamp connector (24) attached thereto. The jumper termination hub (23) is alignable with a riser hub (44) on the second connector part (40) when the first connector part (21) is being tilted relative to the marine riser tower assembly.

Techniques and systems to reduce deflection of a riser extending from an offshore platform. A system may include a riser restraint device configured to be coupled to riser of an offshore platform. The system may also include a tether configured to be coupled to the riser restraint device. The system may further include a ratcheting system configured to be coupled to the tether, wherein the riser restraint device is configured to resist movement of the riser via selective retraction and extension of the tether from the ratcheting system.

A rigid riser system including a rigid riser and one or more fatigue performance enhancers. The rigid riser includes a plurality of rigid metal sections welded together to form a plurality of girth weld joints. The one or more fatigue performance enhancers are positioned over one or more of the plurality of girth weld joints of the rigid riser to enhance the fatigue resistance and/or fatigue life. The body of the fatigue performance enhancer may include a central region and two end regions with the central region having a greater average radial cross-sectional thickness than each of the end regions. Methods of enhancing fatigue performance of the rigid riser and fatigue performance enhancers are also disclosed.

A subsea riser is installed by lowering at least one riser conduit to the seabed when piggybacked to an elongate support that comprises at least one flowline. The elongate support may be a pipeline bundle, which may be attached to one or more towheads in a towable bundle unit. The riser conduit may be in fluid communication with the flowline. At the seabed, a free end portion of the riser conduit is detached from the elongate support by releasing subsea-releasable fastenings. Then, with the elongate support and a root end of the riser remaining at the seabed, the detached free end portion of the riser conduit is lifted away from the elongate support to a riser support, such as a platform, an FPSO (floating production, storage and offloading vessel), or a buoy.

Techniques and systems to reduce deflection of a riser extending from offshore platform. A riser may include an outer enclosure. This outer enclosure may be coupled to a current deflector. The current deflector is configured to generate a lift on the riser in response to a fluid flowing across the current deflector. This lift that is generated by the current deflector may counteract currents or other factors to mitigate deflection in the riser.

A dynamically positioned vessel (DPV) is located above an injection well, inject water or other fluids temporarily or for a short period of time, adjust the injection parameters, and either continue operating for the life of the system or as long as required to add permanent facilities on another platform. The DPV is connected to the potential injection well via a hybrid riser system. The hybrid riser system includes a rigid portion and a flexible portion. Injection using the DPV and the hybrid rise system can be more economical than injection using a conventional mobile offshore drilling unit (MODU) and a rigid riser.

In order to achieve the objects described above, the present invention provides an adapter tool for coupling a ben stiffener with interface for bell mouths of models with connection type BSN900E in a diverless bell mouth (BSDL), consisting of a adapter split ring (1), guide pin holes (C), fastener eyes (D), and through holes (E). The adapter tool is capable of keeping interchangeability and flexibility between projects or project phases, even if different bellmouth models are used. The interconnection method between the helmet (9) and the adapter split ring (1) can be done by direct attachment by bolt, or by attachment by ring/rod support. Both interconnections can be made on board a flexible line launching vessel, in the case of reusing lines from other projects, or at the factory, in the case of sharing new flexible lines.

This invention relates to oil and gas exploration and comprises a direct connection system referred to as a Lower Riser Termination Assembly (LRTA), between risers made of composite material and horizontal lines installed on the seabed (flowlines). The system is applicable to a hybrid riser and its construction method allows cost reduction and system assembly/installation time optimization. The LRTA connection system is applicable to both rigid and flexible flowlines without need for any intermediate connection section/equipment between these and the risers. The construction of the system allows free vertical expansion of the risers along the entire structure. In addition, in the construction method developed for this system, the required area is significantly reduced.