Pipe Spooling for Reel-Lay Operations

A method of spooling first and second pipelines with different inner diameters successively onto a reel, the method comprising:

• assembling the first pipeline from a succession of pipe stalks while, cyclically, filling already assembled pipe stalks with a pressurising liquid, elevating the pressure of the pressurising liquid and spooling the pipe stalks onto the reel while thereby pressurised internally;
• advancing a first, variable diameter pig within the first pipeline to a trailing end of the first pipeline;
• attaching a transition joint to the trailing end of the first pipeline, which transition joint has an inner diameter that transitions from the inner diameter of the first pipeline to the inner diameter of the second pipeline;
• attaching a leading end portion of the second pipeline to the transition joint, that leading end portion containing a second pig in sealing engagement therewith;
• driving the first pig through the transition joint into the leading end portion of the second pipeline, while effecting a change of diameter of the first pig to establish sealing engagement between the first pig and that leading end portion;
• and
• driving the first and second pigs along the second pipeline when assembling the second pipeline from a succession of pipe stalks while, cyclically, filling already assembled pipe stalks with the pressurising liquid, elevating the pressure of the pressurising liquid and spooling the pipe stalks onto the reel while thereby pressurised internally.