Mitigation of buckling in subsea pipelines
AssigneeSubsea 7 Norway AS
InventorsChristian Linde Olsen, Fartein Thorkildsen
Life of this patent
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Abstract
A subsea pipeline (14) has a friction-reducing outer coating, treatment or finish (30) that extends along discrete regions mutually spaced along the length of the pipeline. During laying, curvature is imparted to the pipeline (14) along its length, for example by the residual curvature method or by snake-lay, to create expansion loops (26) of increased curvature relative to intermediate portions (28) of the pipeline (14) that join those loops (26). Each of the loops (26) is coincident with a respective one of the regions that bear the friction-reducing outer coating, treatment or finish (30). This facilitates lateral movement of the loops (26) relative to the seabed (16) to mitigate and control buckling in use of the pipeline (14).
Claims22
A method of laying a subsea pipeline on a seabed, the method comprising:
- launching the subsea pipeline from a pipelaying installation vessel, the subsea pipeline having an outer coating, surface treatment or surface finish extending along discrete regions that are mutually spaced along the subsea pipeline for reducing friction in those discrete regions between an outer surface of the pipeline and soil of the seabed;
- and
- imparting curvature along the length of the subsea pipeline during laying to create expansion loops of increased curvature relative to intermediate portions of the subsea pipeline that join those loops, each of those loops being coincident with a respective one of the discrete regions,
- wherein, once laid, the subsea pipeline and the expansion loops lie in a plane that is substantially parallel to the seabed.
A subsea pipeline laid on a seabed with curvature along the length of the subsea pipeline, the subsea pipeline comprising expansion loops of increased curvature relative to intermediate portions of the subsea pipeline that join those loops, wherein the loops are coincident with respective discrete regions of the subsea pipeline each having an outer coating, surface treatment or surface finish for reducing friction in those discrete regions between an outer surface of the pipeline and soil of the seabed relative to the friction between the outer surface of the subsea pipeline and the soil of the seabed in the intermediate portions of the subsea pipeline, said regions being mutually spaced apart along the length of the subsea pipeline, wherein the subsea pipeline and the expansion loops lie in a plane that is substantially parallel to the seabed.
Dependencies are inferred from the claim text.