Improved stability design of subsea pipelines on mobile seabeds: Learnings from the stablepipe JIP

The on-bottom stability design of subsea pipelines is important to ensure safety and reliability but is challenging to achieve, particularly in Australia due to onerous metocean and seabed conditions, and the prevalence of light gas pipelines. This challenge has been amplified by the fact that industry design guidelines have given no guidance on how to incorporate the potential benefits of seabed mobility, which can lead to lowering and self-burial of the pipeline on a sandy seabed. In this paper, we review the learnings of the STABLEpipe Joint Industry Project (JIP), which was initiated with the aim of developing new design guidelines to assess the on-bottom stability of pipelines on mobile seabeds. The paper summarises the new research undertaken within the STABLEpipe JIP to better predict sedimentation and scour, pipe-fluid interaction and pipe-soil interaction. New design methods to assess the on-bottom stability are also outlined, which have been developed based on the new research. These methods have been adopted in a DNVGL guideline authored by the JIP researchers in collaboration with DNVGL and presently available for use by the JIP participants. Finally, applications of the STABLEpipe JIP outcomes and focus areas for further work are discussed.