Abstract: A subsea foundation for supporting a pipeline or a pipeline accessory has a mudmat and at least one pile arranged to anchor the mudmat by extending from the mudmat into seabed soil. A coupling that couples the pile to the mudmat has at least one interface member supported for angular displacement relative to the mudmat, such as a pivoting beam or a wedge-shaped adaptor ring, to accommodate the orientation of the mudmat relative to the pile.

Abstract: A bearing surface of a subsea foundation has a low-resistance coating such as an aerogel, an aero-clay or a polymeric film. When the foundation is installed, the bearing surface is embedded in the seabed soil using the low-resistance coating to reduce resistance movement of the bearing surface relative to the seabed soil. The coating may then dissolve or fragment away from the bearing surface or transform into a higher-resistance state while remaining on the bearing surface. These mechanisms degrade a resistance-reducing property of the coating to increase resistance to movement of the embedded bearing surface relative to the seabed soil. Suction may be applied to the foundation before or after the resistance-reducing property of the coating has substantially degraded.

Abstract: A pipeline pig launching device has a tubular body that accommodates a set of pipeline pigs arranged in series, such that respective chambers art defined within the body in which to apply launch pressure behind each pig. The body has an open end through which pigs of the set may be launched in succession and a closed end opposed to the open end. A fluid inlet communicates with one of the chambers defined between the closed end and a pig nearest to that closed end. A passageway communicates with another fluid inlet that passageway extending through at least one pig to one or more other chambers defined between successive pigs of the set.

Abstract: A method transports and installs a heavy subsea structure such as a subsea processing center for produced crude oil or natural gas. The method includes controlledly flooding at least one ballast tank attached to or incorporated into the structure to the extent that the structure becomes negatively buoyant at a pre-determined towing depth. The method also includes towing the negatively-buoyant structure at the towing depth by the Controlled Depth Towing Method (CDTM). After towing to the installation location, the method includes further flooding the ballast tank to lower the structure onto the seabed. At the seabed, a fluid transportation pipe of a subsea production installation may be coupled to pipework of the structure.

Abstract: A protective cover for a subsea elongate element, such as a pipeline, has an open end and a barrier attached to a cover to extend across and close an open end. The barrier is flexible to conform to and surround an elongate element extending from under the cover and protruding through the barrier. This prevents rocks of a rock berm from getting under the cover through the open end.

Abstract: 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.

Abstract: A method transports and installs a heavy subsea structure such as a subsea processing center for produced crude oil or natural gas. The method includes controlledly flooding at least one ballast tank attached to or incorporated into the structure to the extent that the structure becomes negatively buoyant at a pre-determined towing depth. The method also includes towing the negatively-buoyant structure at the towing depth by the Controlled Depth Towing Method (CDTM). After towing to the installation location, the method includes further flooding the ballast tank to lower the structure onto the seabed. At the seabed, a fluid transportation pipe of a subsea production installation may be coupled to pipework of the structure.

Abstract: A method of installing an electrically-heatable subsea flowline includes launching the flowline with at least one electric power cable attached in piggybacked relation. After landing the flowline with the piggybacked cable on the seabed, a free end portion of the, or each, cable having a length greater than the water depth is released from the flowline. This allows a free end of the, or each, cable to be recovered to the surface to be spliced to one or more power supply conductors. After lowering the, or each, cable and the, or each, connected conductor beneath the surface, the free end portion of at least one cable is reattached to the flowline on the seabed in piggybacked relation. To perform the method, a subsea flowline assembly includes subsea-releasable fastenings spaced along the cable and the flowline to attach at least an end portion of the cable releasably to the flowline.

Abstract: A wax control element for subsea processing of well fluids in a wellstream comprises a bundle of flowlines within an elongate tensile structure. That structure defines inlet and outlet ends and has cooling and heating provisions that act on the flowlines, in use, to promote deposition of wax in the flowlines and subsequent entrainment of wax in the wellstream.

Abstract: A method of controlling subsea laying of an elongate article includes guiding the article using a submersible vehicle such as an ROV that carries a guide tool. The guide tool has a sleeve through which the article moves axially during laying, while the vehicle applies cross-axial guide forces to the article via the sleeve. Also disclosed is a guide tool including a sleeve through which the article can move axially during laying, and a grab handle whereby a submersible vehicle may hold the tool using a grabber. Alternatively, the guide tool can be attached to or integrated with the vehicle.

Abstract: A method transports and installs a heavy subsea structure such as a subsea processing center for produced crude oil or natural gas. The method includes controlledly flooding at least one ballast tank attached to or incorporated into the structure to the extent that the structure becomes negatively buoyant at a pre-determined towing depth. The method also includes towing the negatively-buoyant structure at the towing depth by the Controlled Depth Towing Method (CDTM). After towing to the installation location, the method includes further flooding the ballast tank to lower the structure onto the seabed. At the seabed, a fluid transportation pipe of a subsea production installation may be coupled to pipework of the structure.

Abstract: A towable unit for subsea processing of well fluids comprises a pipeline bundle extending between, and capable of acting in tension between, a first towhead at an upstream end of the bundle and a second towhead at a downstream end of the bundle. At least one of the towheads has an on-board processing facility for processing the well fluids, which facility effects at least separation of water phases that are present in the well fluids.

Abstract: A method of overboarding and lowering a load from a vessel is disclosed. The method uses a vessel-mounted crane to lift the load from a deck of the vessel, to move the load off the deck into an outboard over-water position, and to lower the load from the outboard position into the water. The method further includes placing at least one guide member acting in compression between the load and an upstanding supporting structure of the crane to restrain horizontal movement of the load relative to a boom of the crane. Then, lowering the guide member occurs to continue restraining horizontal movement of the load while lowering the load from the outboard position into the water. A related guide apparatus includes at least one guide member that is movably connected to a mount for movement relative to the mount around and parallel to a slewing axis of the crane.

Abstract: A carousel for the storage of flexible product, and a method of loading flexible product thereon, wherein said carousel comprises an open drum mounted to rotate around a vertical axis, an elevatable floor, preferably internal to said drum and lifting means for lifting and lowering said elevatable floor. Said lifting means possibly being located between a base of said carousel and said elevatable floor. Said carousel may be of the type designed for location under deck on a marine pipelaying vessel, said flexible product being flexible conduit for the transport of hydrocarbons.

Abstract: A method is disclosed that comprises the steps of preassembling the connector pipe in a support; coupling a frame to the pipeline at or towards an end thereof such that the location of at least one part of the frame is known with reference to the throughbore and the end of the pipeline; engaging the support with a portion of the frame; substantially aligning the connector pipe with the end of the pipeline; and connecting the connector pipe to the end of the pipeline. A cutting tool is also disclosed that can be coupled to a portion of a guide means and used to cut the pipeline at a predetermined distance from the guide means such that the end of the pipeline is created. A remotely operable vehicle can be used to remotely actuate and control the connection of the pipe and the pipeline.