A spring (5;105;205;305;404;505) for a clamp suitable for attachment to a tubular member, the spring comprising a resilient body (6;106;206;306;406;506) having first and second ends (8;108;208;308;408;508) and an internal surface (7;107;207;307;407;507) adapted to seat within a clamp member and an external surface (9;109;209;309;409;509) adapted to contact the outer surface of a tubular member, the internal and external surfaces extending between the first and second ends and wherein the stiffness of the resilient body of the spring varies over the length of the body between the first and second ends.

A riser system with a primary conduit extends between a surface vessel and a subsea location and an auxiliary conduit that extends adjacent the primary conduit. In one example a composite jumper conduit extends from the surface vessel and is fluidly connected to the auxiliary conduit. The jumper conduit includes a composite material formed of at least a matrix and one or more reinforcing elements embedded within the matrix. In one example a subsea composite jumper conduit extends from subsea infrastructure and is fluidly connected to the auxiliary conduit. The subsea jumper conduit includes a composite material formed of at least a matrix and one or more reinforcing elements embedded within the matrix.

A protective member at least partially surrounds a desired length of pipe (such as a conventional landing string) and protects “umbilical” control line(s) or bundles, including pipe and umbilical line(s) installed within risers of subsea installations. At least one robust protective shell member is installed around at least a portion of a pipe string and forms at least one elongated channel. At least one umbilical control line is disposed within the elongated channel and is shielded against damage from inadvertent or unwanted abrasion, impact or other forces.

Offshore production systems and methods relating thereto are disclosed. In an embodiment, the offshore production system includes a surface vessel. In addition, the offshore production system includes a closed-loop cooling fluid circulation system extending subsea from the vessel and configured to cool a cooling fluid. The closed-loop cooling fluid circulation system includes a first tendon having an upper end coupled to the surface vessel and a lower end coupled to the seabed. The first tendon is in tension between the upper end and the lower end. The first tendon is configured to flow the cooling fluid from the lower end of the first tendon to the upper end of the first tendon.

A subsea catenary riser comprises a rigid riser pipe that is suspended from a floating support on the surface and extends through a sagbend to the seabed. A hang-off interface allows rotation or pivoting of the riser pipe relative to the support about mutually orthogonal horizontal axes. A subsea buoy is positioned on the riser pipe above the sagbend. The buoy applies buoyant upthrust force to the riser pipe via an attachment interface that allows rotation or pivoting of the riser pipe relative to the buoy about mutually orthogonal horizontal axes. In response to movement of the support, the riser pipe deflects with S-shaped curvature to vary the inclination, relative to the buoy, of the portion of the riser pipe to which the buoy is attached. The curvature comprises mutually opposed curves respectively above and below the buoy, joined by a region of inflection that coincides with the buoy.

A buoyancy module (10, 12, 14) configured for mounting on an elongate underwater member (16) and provided with a sensor module dock (32) for receiving and releasably retaining a sensor module (30).

A method of installing a subsea riser comprises 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 5 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 comprises a riser support disposed in a longitudinally-extending open-ended gap between buoyancy volumes disposed on opposite sides of 0 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.

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.

Some embodiments are directed to a process for making a syntactic foam. Some other embodiments are directed to a process for manufacturing a buoyancy material including an outer shell and a syntactic foam. Still other embodiments are directed to the syntactic foam (or buoyancy foam) obtainable by this process. Some other embodiments are directed to a process of undersea extraction of oil including: using the syntactic. Still other embodiments are directed to an undersea extracting pipeline including a pipeline, and either the syntactic foam or the buoyancy material.

A method of manufacturing marine riser buoyancy elements includes providing a master mold and mold inserts such that a range of buoyancy elements may be manufactured from one master mold and providing the mold inserts such that an annular space between the riser main conduit and the buoyancy elements, or a groove width between the buoyancy elements may be varied during manufacture.