A method of installing a subsea riser includes placing an elongate negatively-buoyant support on the seabed and, when laying the riser on the seabed, guiding a riser portion onto the support to extend along and be cradled by the support. A hogbend region of the riser is then formed by conferring positive buoyancy on the support to lift the support and the riser portion away from the seabed. An element of the support includes a riser support disposed in a longitudinally extending open-ended gap between buoyancy volumes disposed on opposite sides of the gap. Coupling formations such as hinge portions can couple the element to a like element. When so coupled, the gaps of those elements align to define an upwardly opening, longitudinally extending groove to receive the riser.

An element for a bend restrictor including a first part and a second part which together provide a cavity for receipt of a flexible pipe, in use, the two parts are pivotably connected together at a first portion thereof and are releasably coupled or couplable together at a second portion thereof. Successive elements may be secured together to form a bend restrictor.

A creep resistant material comprises a core layer (12) of rigid polyurethane with a first tensile reinforcement layer (17) applied on one surface and a second tensile reinforcement layer (17) applied on the other opposed surface of the core layer, the entire respective first and second tensile reinforcement layers being in contact with the first and second surface of the core layer of the material.

This invention provides a system and a method for supporting the operation of subsea installations for 3D reconstruction of flexible pipes (1) during a direct vertical connection operation, comprising the steps of painting the flexible pipe (1) with a specific regular pattern, and performing a 3D reconstruction of the points sampled on the flexible pipe (1) to obtain the radius of curvature of the flexible pipe (1), in which the 3D reconstruction comprises the steps of: capturing images of the flexible pipe (1) during the direct vertical connection operation; sending the captured images to a dedicated computer (4); and processing the captured images, generating information on the radius of curvature, wherein the method initially comprises at least one of the following steps: painting the bend restrictor (6) with a specific regular pattern; painting straps (71) for buoys (7) with a specific regular pattern; and painting straps (71) for the arch bend, in the event of second-end direct vertical connection.

A method for controlling buckling in subsea pipelines involves identifying spaced-apart sections of a subsea pipeline suitable for controlled lateral buckling. Sets of buoyancy modules are installed at each spaced-apart section and are selected to support the spaced-apart sections of the subsea pipeline in a neutrally buoyant condition at the seafloor when the subsea pipeline is in service. Any buckling caused by thermal expansion of the subsea pipeline is distributed to two or more of the spaced-apart sections, causing the two or more spaced-apart sections to deflect laterally along the seafloor outwardly from an initial as-laid position.

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.

A subsea hydrocarbon export system includes a riser tower having a riser column extending from a seabed location to a sub-surface buoy that supports the riser column in an upright orientation. A subsea connector is operable underwater to couple the riser column temporarily to a hose suspended from a surface shuttle tanker vessel for an export operation and to release the hose after the export operation.

A coupling system (12) between a riser (2) and an underwater supporting structure (10), includes a coupling seat (13) and a coupling head (14) which can be inserted in the seat. A pull connector (16) constrains the head (14) to the seat (13) to prevent the extraction of the head (14) but to allow rotation of the head (14). A clamping connector (18) constrains the head (14) to the seat (13) to prevent transversal translation and rotation to the head (14) and the seat (13). The pull connector (16) can be actuated alone and independently from the clamping connector (18) to make a provisional, pull-only connection between the head (14) and the coupling seat (13). The clamping connector (18) can be actuated independently from the pull connector (16) to allow postponing the complete clamping with respect to the provisional connection.

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.

Another important feature of the presented system is the fact that its construction allows free vertical expansion of the risers along the entire structure.

In addition, while, in the state of the art, the conventional methods require a large assembly and construction area, in the construction method developed for this system, the required area is significantly reduced, approximately 10 times smaller than that required for known construction methods.

A downhole apparatus includes a casing string with a fluid barrier connected therein defining a lower end of a buoyancy chamber. A rupture disk is spaced from the fluid barrier and defines an upper end of the buoyancy chamber. A degradable plug is connected in the casing string above the rupture disk. The degradable plug defines a flow path to permit flow therethrough to the rupture disk, and is movable from a first to a second position in the casing string.