A pipeline bundle for a riser tower or tie-back is manufactured offshore by suspending the bundle from an installation vessel, adding structural core sections successively to an upper end of the suspended bundle, lowering the bundle after adding each successive core section, and feeding one or more lengths of flowline pipe beside the core sections for incorporation into the bundle. The flowline pipe is coiled on a reel or carousel as a full-length piece before being uncoiled progressively as core sections are added to the lengthening bundle. The flowline pipe is then engaged with guide frames and/or buoyancy blocks supported by the core sections, by movement in a radially-inward direction through a radially-outer opening in a retainer formation. The opening is then closed to hold the flowline pipe in the retainer formation.

A method of laying a pipeline from a laying vessel into a body of water includes guiding the pipeline along a supporting structure of a laying ramp. The method also includes acquiring a first data item correlated to a position of the pipeline at a free end of the laying ramp using an optical sensor or an acoustic sensor. The method further includes determining whether the acquired first data item is within an acceptance range predetermined as a function of a configuration of the supporting structure and a size of the pipeline. Additionally, the method includes emitting an control signal when the acquired first data item is not within the acceptance range. Determining whether the acquired first data item is within the acceptance range includes processing the acquired first data item to compare it the first data item to an information stored in a memory.

A method of laying a pipeline from a laying vessel into a body of water includes guiding the pipeline along a supporting structure of a laying ramp. The method also includes acquiring a first data item correlated to a position of the pipeline at a free end of the laying ramp using an optical sensor or an acoustic sensor. The method further includes determining whether the acquired first data item is within an acceptance range predetermined as a function of a configuration of the supporting structure and a size of the pipeline. Additionally, the method includes emitting an control signal when the acquired first data item is not within the acceptance range. Determining whether the acquired first data item is within the acceptance range includes processing the acquired first data item to compare it the first data item to an information stored in a memory.

In a method of joining a structure to a water-filled pipeline aboard a reel-lay vessel, a trailing end portion of the pipeline is suspended upright on a reel-lay tower. Water is drained from the trailing end portion while being retained in an inclined portion of the pipeline extending from the tower to a reel of the vessel and in a spooled portion of the pipeline coiled on the reel. The structure is joined to a trailing end of the pipeline after inserting a pig into the trailing end portion through the trailing end. Pumping additional water into a leading end of the pipeline on the reel propels the pig from the trailing end portion into a conduit of the structure while flooding the trailing end portion. This expels air through a port of the structure that was trapped in the trailing end portion between the pig and the structure.

A portion of a line from a line laying vessel to a touchdown support point on or near to the seabed is imaged with a 3 dimensional sonar imaging system to produce coordinates of a series of touchdown points using a time sequence of sonar images, and the time series of touchdown points is recorded.

A portion of a line from a line laying vessel to a touchdown support point on or near to the seabed is imaged with a 3 dimensional sonar imaging system to produce coordinates of a series of touchdown points using a time sequence of sonar images, and the time series of touchdown points is recorded.

A method of installing a subsea pipeline for tie-in to a subsea structure includes laying, using a pipe laying vessel, an intermediate section of the pipeline on to a pipe restraint device, wherein the pipe restraint device is at or near the subsea structure, or is at or near a location at which a subsea structure will be installed, and the pipe restraint device restricts transverse movement of the pipeline. The intermediate section of the pipeline is configured to be tapped at or near the pipe restraint device for providing fluid communication between the pipeline and the subsea structure.

A method of installing a subsea pipeline for tie-in to a subsea structure includes laying, using a pipe laying vessel, an intermediate section of the pipeline on to a pipe restraint device, wherein the pipe restraint device is at or near the subsea structure, or is at or near a location at which a subsea structure will be installed, and the pipe restraint device restricts transverse movement of the pipeline. The intermediate section of the pipeline is configured to be tapped at or near the pipe restraint device for providing fluid communication between the pipeline and the subsea structure.

A method of installing a subsea tie-in conduit comprises unspooling or manufacturing a steel rigid lined pipeline (14) aboard an installation vessel and launching the pipeline progressively from the vessel (10) into water. A distal end of the tie-in conduit is coupled to a proximal end of the pipeline above the surface and is then launched into the water coupled to the pipeline. The suspended weight load of the pipeline is supported by an A&R wire (34) connected to the proximal end (38) of the pipeline, defining a load path that bypasses the tie-in conduit (30). A proximal end of the tie-in conduit may be suspended from that wire. The tie-in conduit is of composite or flexible pipe, hence being pliant relative to the lined rigid pipeline and maintaining its internal corrosion resistance. After landing on the seabed, the tie-in conduit may be deflected relative to the pipeline for connection to a subsea connection point.

A method of installing a subsea tie-in conduit comprises unspooling or manufacturing a steel rigid lined pipeline (14) aboard an installation vessel and launching the pipeline progressively from the vessel (10) into water. A distal end of the tie-in conduit is coupled to a proximal end of the pipeline above the surface and is then launched into the water coupled to the pipeline. The suspended weight load of the pipeline is supported by an A&R wire (34) connected to the proximal end (38) of the pipeline, defining a load path that bypasses the tie-in conduit (30). A proximal end of the tie-in conduit may be suspended from that wire. The tie-in conduit is of composite or flexible pipe, hence being pliant relative to the lined rigid pipeline and maintaining its internal corrosion resistance. After landing on the seabed, the tie-in conduit may be deflected relative to the pipeline for connection to a subsea connection point.