Deepwater HPHT pipelines are generally susceptible to significant end expansion and axial walking. Pipeline walking can cause cumulative axial displacement of the entire pipeline, which can induce damage at termination units, expansion spools and riser tie-ins. The rate of walking depends not only on the temperature profiles, but also on the magnitude of axial resistance, the mobilization distance and the seabed topography.

In this paper, Filip Van den Abeele, Jean-Christophe Ballard and Charles de Brier from Fugro GeoConsulting (Belgium) present parametric FE analyses performed with SAGE Profile. The results indicate that the powerful pipe-soil interaction library of SAGE Profile is capable of accurately capturing the phenomenon of axial walking

More sophisticated axial pipe-soil responses, derived from the SMARTPIPE measurements, were implemented to assess the impact on the predicted and expansion walking rate. The axial pipe-soil interaction was captured by a tri-linear soil spring, and the effects of mobilization distance, peak friction factor and residual friction factor were evaluated by performing sensitivity analyses. Moreover, the tri-linear soil spring in SAGE Profile allows distinguishing between the initial (first loading) stiffness, the unloading stiffness and the reloading stiffness.

 >> Read more – 2013