Reeling is a fast, reliable and cost effective method for installing subsea flowline systems up to 20 inch in diameter. The individual flowline joints are lined up and welded together onshore to make long stalks of pipe before being spooled onto the large reels of reel lay vessels. On arrival in the field offshore, it is spooled off, straightened and laid on the seabed up to 10 times faster than conventional S-lay or J-lay methods. The ability to carry out the fabrication and welding onshore, off-line from the vessel critical path, allows very high quality welding and coating to be achieved.
Over the last few years, it is evident that the engineering fundamentals, mechanics and cost effectiveness of the reeling process are now well understood within different quarters of the offshore industry as many major pipelaying Contractors own, or are planning to own, a reel lay vessel. What is apparently missing, however, is the implications and practical aspects of the reeling process when it comes to implementation during project execution.
This paper reviews the engineering fundamentals of the reeling process first and then discusses the practical aspects and applications of reeling mechanics from spoolbase fabrication to spooling-on process up to the offshore campaign and spooling-off process and subsea installation.