Abstract: A method of abandoning a pipeline during subsea pipelaying from a pipelay vessel includes suspending the pipe string from a tendon element of an abandonment string and engaging further tendon elements to an upper end of the abandonment string while lowering the pipe string to a handover depth. At the handover depth, tension is applied via a wire to the top of the pipe string at an acute angle to the launch axis. This deflects the pipe string from the launch axis into axial alignment with the wire to transfer the weight load of the pipe string to the wire, whereupon the abandonment string can be decoupled from the pipe string. Recovery of the pipeline from the seabed can be effected by a reverse process.

Abstract: A connector for lined pipelines includes a tube having opposed male interface elements extending inwardly from respective ends of the tube. One or more circumferential permeable chokes project radially from each male interface element. The chokes minimize flow of oxidizing fluid from the bore into the micro-annulus between the liner and the pipe while maximizing flow of fluid from the micro-annulus into the bore in the event of catastrophic pressure drop in the bore. To maintain gaps between the tube ends and the pipe liners for fluid flow, shoulder formations defined by radially-projecting bands extend circumferentially around the tube. The connector may be used in a joint arrangement where each liner includes a body section, an end section of lesser thickness and greater bore than the body section that terminates short of an end of the pipe, an inner step disposed between the body section and the end section, and an outer step disposed between the end section and the pipe.

Abstract: A thermoplastics injection moulding process coats a field joint of a pipeline by positioning a mould tool around the field joint to define a mould cavity. Thermoplastics material injected into the mould cavity forms a field joint coating that will set in the mould cavity. As the thermoplastics material shrinks in the mould cavity while the field joint coating sets, compacting pressure is applied radially inwardly within the mould cavity against a radially outer side of the field joint coating. A compacting fluid introduced into the mould cavity between the mould tool and the field joint coating may be used to apply pressure against the field joint coating. This accelerates and controls cooling of the field joint coating while maximising quality.

Abstract: A subsea riser support buoy is disclosed having a riser support member and a jumper support member that extend generally parallel to each other and that define a lengthwise direction extending between them across the buoy. Pontoons extend lengthwise beyond the riser support member and the jumper support member to provide attachment points for connecting tethers to the buoy. In this way, the attachment points are spaced more widely than lengthwise extremities of the riser support member and the jumper support member, beneficially altering the dynamic behavior of the buoy and especially its pitch characteristics.

Abstract: A subsea payload such as an AUV (autonomous underwater vehicle) or an AUV garage is lifted from an underwater location by flying a latch unit through the water to the payload. The latch unit carries a lift line toward the payload. The latch unit is then attached to the payload and the payload is lifted using tension applied through the lift line via the latch unit. The latch unit can also be used on a lift line to lower a payload and then to release the payload at an underwater location. The lift line is supported by a heave-compensating winch on a surface vessel that effects z-axis movement of the latch unit. The winch maintains tension on the lift line to prevent the lift line falling on the payload. Movement of the latch unit on x- and y-axes is effected by on-board thrusters.

Abstract: A subsea pump system is adapted to close a hydraulic ram of a blowout preventer. The subsea pump system has at least a first pump and a second pump configured to pump drive fluid from a source to the hydraulic ram. The system has a controller configured to automatically select at least one of the first and second pumps for pumping the drive fluid wherein at least the first pump is selected at a lower fluid pressure range and at least the second pump is selected at a higher fluid pressure range. A method of operating a pump system and an intervention skid for a pump system are also described.

Abstract: A top connector for a tether of a subsea buoy is disclosed. The connector has a support, a lever member movable about a pivot axis, and a chain stop mechanism mounted on the lever member to be situated below the pivot axis in use. The lever member is pivotably connected to the support via a flex joint arranged to bear a tensile load exerted by a top chain of the tether when engaged with the chain stop mechanism. The flex joint improves bending fatigue life of the top chain. A frame extends upwardly from the support to carry a sheave for the top chain. A pivotably connected lever member extends downwardly from the support. The lever member is pivotable relative to the support and the frame, allowing a compact arrangement that avoids the frame, the top chain or the sheave clashing with the shell of the buoy.

Abstract: An apparatus for clamping elongate elements in a parallel piggybacked arrangement during subsea laying of the elements is disclosed. The apparatus has opposed reciprocating jaws for forcing together clamp segments around the elongate elements to assemble a piggybacking clamp that applies clamping forces to the elongate elements.

Abstract: A method of installing a production buoy at a subsea anchoring location is disclosed. The method includes floating a production buoy over a subsea anchoring location. Then, hanging at least a tether off the production buoy such that the or each tether extends from the production buoy towards the subsea anchoring location occurs. The method includes submerging the production buoy to a depth which allows connection of the or each tether to the subsea anchoring location. An apparatus suitable for use with this method is also provided.

Abstract: A floatable spoolbase for supplying rigid pipe to a reel-lay pipelaying vessel having a storage reel with an upright rotational axis for interim storage of a continuous length of pipe is disclosed. Welding stations upstream of the storage reel add pipe elements to the pipe to be stored on the storage reel. When a pipelaying vessel visits the spoolbase, the pipe is unwound from the storage reel and fed to a pipelay reel of the pipelaying vessel. Where the pipelay reel turns about a substantially horizontal rotational axis, winding the pipe onto the pipelay reel reduces ovalization of the pipe imparted by previously winding the pipe onto the storage reel.

Abstract: A method and connecting apparatus for attaching a pipeline termination assembly to a subsea structure. The pipeline termination assembly has a pivot axis member and the subsea structure has one or more capture slots to receive it. The pivot axis member is captured in the capture slot, the slot allowing vertical movement of the pipeline termination assembly. The pipeline termination assembly is rotated about the pivot axis to assume a horizontal position. In the horizontal position, the capture slot permits horizontal movement of the pipeline termination assembly. A capture device mounted on the subsea structure provides the capture slots. At least a part of the capture device is moved with respect to the subsea structure to retain the pivot axis member in the capture slot on rotating the pipeline termination assembly about the pivot axis.

Abstract: A rigid-to-flexible connector (RFC) is provided on the rigid pipe section instead of a pipeline end termination (PLET), and the pipe end having the RFC is raised to the surface of the sea, while leaving a portion of the rigid pipe section on the seabed. The RFC is then connected to one end of the flexible pipe section, and the latter lowered to the seabed, with the raised, end of the rigid pipe section attached, to return the rigid pipe section to the seabed. Since the RFC on the rigid pipe section is connected to the flexible pipe section at the surface of the sea, the RFC can have a simpler, lighter, technical design, resulting in significant cost, manufacturing time and quality control time savings.

Abstract: A seabed-to-surface riser system is disclosed. The seabed-to-surface riser system has a group of subsea riser supports that each support riser pipes extending from the seabed to mid-water. Jumper pipes extend from there to a floating production, storage and offloading (FPSO) offset horizontally from the riser support in a flow direction. The group of riser supports is disposed to one side of the surface installation. Laterally-extending lines are attached to at least the outermost riser supports of the group. Those lines apply mutually-opposed stabilizing forces to those outermost riser supports in directions transverse to the flow direction.

Abstract: A subsea anchoring assembly with a locking head for connection of a mooring line to an anchor is disclosed. A socket is provided on the anchor. The socket has a seat adapted to receive and seat the locking head within it. The socket has a neck provided with a guide device to direct the locking head into alignment with the socket. By this arrangement, the locking head and the socket can move between a first configuration in which the locking head and the socket are separate, and a second configuration in which the locking head and the socket are locked together. An associated method is also described.

Abstract: A piggybacking clamp for subsea laying of two or more elongate elements in a piggybacked arrangement is disclosed. The piggybacking clamp has a plurality of clamp segments assembled to surround and clamp the elongate elements. Each clamp segment has two or more generally parallel mutually spaced recesses shaped to extend partially around respective ones of the elongate elements. The piggybacking clamp additionally has retainers that hold the clamp segments together when assembled, such that the assembled clamp segments apply clamping forces to the elongate elements in the recesses.

Abstract: An alignment tool for aligning a secondary elongate element with a primary elongate element for subsea laying of the elements in a piggybacked arrangement is disclosed. The alignment tool comprises a support structure arranged to embrace the primary element. The support structure has an opening for accommodating the primary element such that the primary element can move longitudinally through the opening in a launching direction. The alignment tool further comprises attachment points for supporting the tool to maintain or control its longitudinal and/or angular position with respect to the primary element as the primary element moves through the opening.

Abstract: Apparatus and method for overhauling a flanged coupling of joined conduit components including a gripping mechanism that straddles the flange-coupling and grips both flange-coupled components. The gripping mechanism is mounted on a lifting frame and bears the loadings upon the gripped tubular components during a moving operation. The apparatus also includes a collar sized to fit over the flange-coupling and located in spaced apart cradles supported on a base frame. The cradles are configured to receive the flange-coupled tubular components and position the collar for closure about the flange-coupling. The collar is provided with fasteners for closure of the collar about the flange-coupling, and a fastening mechanism operating the fasteners to secure the collar when closed about the flange-coupling.

Abstract: A method of installing a production buoy at a subsea anchoring location is disclosed. The method includes floating a production buoy over a subsea anchoring location. Then, hanging at least a tether off the production buoy such that the or each tether extends from the production buoy towards the subsea anchoring location occurs. The method includes submerging the production buoy to a depth which allows connection of the or each tether to the subsea anchoring location. An apparatus suitable for use with this method is also provided.

Abstract: A lifting block and a method of using it for supporting a load from a first lifting device or sharing the load between the first lifting device and a second lifting device, particularly for use on a vessel and deep water applications, are disclosed. The lifting block, with at least one sheave, has first and second connection elements associated with it. In one arrangement (single fall) a lifting wire or rope is fed around the sheave and terminated in an end stop which also provides the first connection element. When the first lifting device is operated alone, the end stop rests on the block. When the second connection element, secured to the lifting wire or rope of a second lifting device, is joined to the first connection element the load is snared between the two lifting devices which can then be operated in unison to position the load at a required, deeper position.

Abstract: Apparatus and method for handling a fluid-tight flange coupling between a first and a second conduit component while maintaining the fluid integrity of the coupling. The apparatus includes a gripping mechanism configured to straddle the flange coupling and grip both of the first and second conduit components. The gripping mechanism is mounted on a lifting frame able to bear the loadings upon the gripped components during a moving operation. The apparatus includes a base frame with a gripping mechanism to receive the flange coupling. The coupled components are gripped on each side of the flange coupling to maintain the fluid integrity of the flange coupling.