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.

The invention relates to a self-propelled valve actuator on a rail transport system for manifolds and Christmas trees. The valve actuator is moveable along a transport rail and may operate several valves. The valve actuator is driven by a gearwheel motor. The invention also relates to a rotatable valve head having diametrical slots with which the valve actuator may interact.

A process system includes a process module, an upstream pipe, a downstream pipe, an inlet pipe with an inlet isolation valve, an outlet pipe with a discharge isolation valve, a bypass with a bypass isolation valve, and a drainage line with a valve. The process module has an inlet, an outlet, and a drainage outlet. The inlet pipe fluidically connects the inlet of the process module to the upstream pipe. The outlet pipe fluidically connects the outlet of the process module to the downstream pipe. The bypass fluidly connects the upstream pipe and the downstream pipe via the bypass isolation valve. The drainage line fluidly connects the drainage outlet of the process module to the downstream pipe via the valve.

A well production system comprises a safety instrumented system (SIS) having one or more logic solvers; one or more pressure transmitters disposed along a flowpath and communicatively coupled to the one or more logic solvers; one or more valves disposed along the flowpath and communicatively coupled to the SIS, wherein the SIS is configured to selectively actuate the one or more valves based on feedback from the one or more pressure transmitters; and a spare pressure transmitter disposed along the flowpath, wherein the spare pressure transmitter is configured to be selectively coupled to the one or more logic solvers.

A method for transmitting signals in a subsea environment includes determining that a quality of an acoustic signal is below a threshold. The acoustic signal travels from a first device, through water in the subsea environment, to a second device. A parameter of the first device, the second device, or both is then adjusted to improve the quality of the acoustic signal when the quality of the acoustic signal is below the threshold.

A subsea hydrocarbon flowline system (300) is disclosed. The flowline system has a hydrocarbon flowline (302); an electric trace heating system (304) arranged along at least a part-length of the flowline to control the temperature of hydrocarbon fluid flowing in the flowline; and a power input connector (Pin) configured for receiving electrical power from an electrical power providing system for powering the electric trace heating system. The electric trace heating system has a first three-phase trace heating cable (C′) and a second three-phase trace heating cable (C″), each trace heating cable extending between the power input connector and a cable termination (T′; T″) where phase conduits (L1′, L2′, L3′; L1″, L2″, L3″) of the trace heating cable are Y-connected and terminate in a neutral connection point (L.sub.N′; L.sub.N″). Further, the flowline system has a power output connector (Pout) for providing electrical power to a subsea hydrocarbon production system; a first electrical conduit (306′) extending between the neutral connection point of the cable termination of the first trace heating cable and the power output connector; and a second electrical conduit (306″) extending between the neutral connection point of the cable termination of the second trace heating cable and the power output connector, wherein the first and the second electrical conduits are electrically accessible at the power output connector for powering the subsea hydrocarbon production system.

A tensioning system includes a combined rope gripper and tension cylinder. A rope passes through the combined rope gripper and tension cylinder. Once the length and/or tension of the rope has been adjusted, a reel lock handle can be actuated to prevent further rotation of the reel. The combined rope gripper and tension cylinder can be actuated to hold the rope. The combined rope gripper and tension cylinder can also be actuated to reduce or prevent the release of tension in the rope.

A subsea well intervention cap is provided. The subsea well intervention cap includes a frame, a first clamp segment coupled to the frame and configured to be fitted over a horizontally oriented flowpath of a subsea well equipment component, and a second clamp segment having a rim segment configured to interface with the first clamp segment, wherein the second clamp segment is movable with respect to the first clamp segment. The subsea well intervention cap also includes an actuation mechanism coupled to the frame that actuates the second clamp segment in a vertically upward direction and in an axial direction with respect to the frame toward the first clamp segment. The subsea well intervention cap is lightweight and able to be installed on subsea well equipment using a standard remote operated vehicle (ROV).

There is described the processing seawater in a subsea facility on the seabed in various methods and apparatus. In various examples, the facility is coupled to at least one well, is configured to provide the well with water to be injected into at least one formation of the well, and comprises filter elements arranged in housings, the filter elements being configured for ultrafiltration or microfiltration. In such examples, treated seawater in at least one of the housings is filtered using at least one filter element, producing thereby filtered water, and at least one filter element in at least one other of the filter housings is cleaned by backwashing performed using at least some of the produced filtered water.

A connection assembly for engaging a tubular member underwater to restrain the tubular member from radial movement relative to the connection assembly includes a plurality of pads for engaging the tubular member at circumferentially spaced positions; and a plurality of biasing arrangements, each for biasing a respective pad radially inwardly into engagement with the tubular member; wherein each biasing arrangement includes a pre-loadable, mechanical, compressed spring arrangement for resiliently pressing its respective pad against the tubular member. The assembly need not employ any hydraulic components.