J-Lay pipeline installation method is frequently used in deep water pipeline installation. The curvature of pipe line is similar to J shape (Figure 1) while the subsea pipeline is being installed. J-Lay method can handle a full range of pipeline size and it is particularly suitable for deep water pipeline installation up to 2,000 m (6,560 ft). Furthermore, the J-Lay method can withstand higher underwater current and sea state than the S-Lay method.
The J-lay method puts less stress on the pipe line because the pipeline is installed in an almost vertical position. Whereas the S-lay method puts on more stress due to two curvatures at the sag bend and over-bend region. The pipeline is sent into water at a small angle reference to a vertical line and continues at a steep angle until a sag bend is formed.
This works very well in deep water environment where distance from a vessel to a touchdown point is quite far because sag bend is not too much. If the short distance from a vessel to a touchdown point.
This video demonstrates how J-Lay method works.
Example of a J-Lay Pipe Vessel
Saipem 7000 Lay Barge
J-Lay tower handles quadruple jointed pipe
Laid Blue Stream twin pipeline across Black Sea:
− Maximum water depth 2,150 m BMSL.
− Pipeline OD = 24”. WT 1.25”
Heavy lift cranes rated at 14,000 mT.
James G. Speight, 2014. Handbook of Offshore Oil and Gas Operations. 1 Edition. Gulf Professional Publishing.
Trond Bendiksen, 2015. Commissioning of Offshore Oil and Gas Projects: The manager’s handbook. Edition. AuthorHouse.
Joseph A. Pratt, 1997. Offshore Pioneers: Brown & Root and the History of Offshore Oil and Gas. Edition. Gulf Professional Publishing.
Gazprom.com, (2012), Saipem 7000 Lay Barge [ONLINE]. Available at: http://www.gazprom.com/f/posts/14/420254/04881_005.jpg [Accessed 24 July 2016].