A system for laying an underwater pipeline on a bed of a body of water has a construction site to form a string of an underwater pipeline, the string being defined by a curved portion shaped substantially like a portion of the bed of the body of water characterized by an abrupt change in slope; at least two vessels to transfer, in the body of water, the string from the construction site to a laying site in the body of water and substantially on the vertical of a path along which to lay the string; and a plurality of floating devices configured to be coupled to the string and so as to selectively support and sink the string in the body of water, and progressively lay the string along the path on the bed of the body of water.

A system for laying an underwater pipeline on a bed of a body of water has a construction site to form a string of an underwater pipeline, the string being defined by a curved portion shaped substantially like a portion of the bed of the body of water characterized by an abrupt change in slope; at least two vessels to transfer, in the body of water, the string from the construction site to a laying site in the body of water and substantially on the vertical of a path along which to lay the string; and a plurality of floating devices configured to be coupled to the string and so as to selectively support and sink the string in the body of water, and progressively lay the string along the path on the bed of the body of water.

A long steel pipe for reel-lay installation formed of electric resistance welded (ERW) steel pipes and having high buckling resistance and a method for producing the long steel pipe for reel-lay installation are provided. The long steel pipe is formed by successively butt-joining longitudinal ends of the ERW steel pipes by girth welding so that girth welds are formed. The ERW steel pipes are successively butt-joined in the pipe longitudinal direction such that the 0 o'clock cross-sectional position or the 6 o'clock cross-sectional position of one of adjacent ERW steel pipes faces an area from the 2 o'clock cross-sectional position to the 4 o'clock cross-sectional position or an area from the 8 o'clock cross-sectional position to the 10 o'clock cross-sectional position of the other of the adjacent ERW steel pipes.

A method of clamping elongate elements in a parallel piggybacked arrangement during subsea laying of the elements is disclosed. The method includes opposed reciprocating jaws which force together clamp segments around the elongate elements to assemble a piggybacking clamp. The piggybacking clamp applies clamping forces to the elongate elements.

The present invention provides an improved pipeline burying apparatus that uses specially configured jetting nozzles that intake sea water surrounding the nozzle. The apparatus provides a frame supporting spaced apart left and right inclined pipe sections that are configured to be placed on opposing sides of the pipeline to be buried. Each inclined pipe section is fitted with a plurality of jetting nozzles that are positioned on one of the inclined pipe sections, in vertically spaced apart positions and in horizontally spaced apart positions. At least some of said jetting nozzles include a nozzle body having an outer surface and a main, central longitudinal fluid flow channel with a central channel axis. A fluid inlet end portion of the nozzle body has an externally threaded portion that enables connection to an internally threaded portion of a selected one of the inclined pipe sections. A discharge end portion of the nozzle body extends outwardly from an inclined pipe and the threaded portion. A plurality of lateral channels each intersect the main channel at an acute angle. In one embodiment, the main central longitudinal channel has an inlet section with an inlet section diameter, a discharge section having an outlet section diameter and a connecting section that is in between the inlet section and the outlet section.

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.

Disclosed are processes for removing carbon steel components of a subsea oilfield facility in a subsea environment by accelerating the corrosion of the carbon steel components in the surrounding seawater, by a passive and/or active impressed current method. In the passive method, the facility is connected to a cathodic metal of greater electrical potential, such as copper. In order to cause the maximum and uniform corrosion, it is preferred that a wire of the chosen cathodic metal be extended along the facility and through pipelines. In the active impressed current method, an external DC electrical supply is used to apply an electrical potential difference between the steel components of the facility and the cathodic metal.

A method for installing an accessory onto a pipeline to be laid on the seabed, includes launching the pipeline from a first position of a tower in which the tower is at an angle α with respect to the vertical; stopping the launch of the pipeline, and hanging off the launched pipeline in a hang off module; positioning an accessory in a tower firing line; attaching the accessory to the launched pipeline in the hang off module and to at least one A&R cable; suspending the accessory and the launched pipeline from an A&R system; disengaging the hang off module from the launched pipeline; pivoting the pipeline launch tower to an accessory launch position in which the tower is at an angle γ that differs substantially from angle α, such that a pipeline launch trajectory is created which is large enough to launch the accessory and the launched pipeline with the A&R system.

A method for installing an accessory onto a pipeline to be laid on the seabed, includes launching the pipeline from a first position of a tower in which the tower is at an angle α with respect to the vertical; stopping the launch of the pipeline, and hanging off the launched pipeline in a hang off module; positioning an accessory in a tower firing line; attaching the accessory to the launched pipeline in the hang off module and to at least one A&R cable; suspending the accessory and the launched pipeline from an A&R system; disengaging the hang off module from the launched pipeline; pivoting the pipeline launch tower to an accessory launch position in which the tower is at an angle γ that differs substantially from angle α, such that a pipeline launch trajectory is created which is large enough to launch the accessory and the launched pipeline with the A&R system.

A subsea riser is installed by lowering at least one riser conduit to the seabed when piggybacked to an elongate support that comprises at least one flowline. The elongate support may be a pipeline bundle, which may be attached to one or more towheads in a towable bundle unit. The riser conduit may be in fluid communication with the flowline. At the seabed, a free end portion of the riser conduit is detached from the elongate support by releasing subsea-releasable fastenings. Then, with the elongate support and a root end of the riser remaining at the seabed, the detached free end portion of the riser conduit is lifted away from the elongate support to a riser support, such as a platform, an FPSO (floating production, storage and offloading vessel), or a buoy.