Estimation of Pipeline Embedment in Soft Submarine Soils by Different Methods

The embedment of subsea pipelines in soft submarine clay is a key parameter in pipe-soil interaction studies of offshore deep water oil and gas field developments. A number of calculation methodologies exist, some of which are based on empirical evidence. Pipeline embedment depends on the active undrained shear strength and unit weight of the soil and the properties of the pipeline (i.e. weight and dimensions). The embedment is also influenced by stress concentrations occuring due to the geometry of the pipe catenary and by the cyclic motion of the catenary at the touchdown point. In this study, the methods typically used in the industry, such as those proposed by Terzaghi (1967), Dunlap et al. (1990) and Verley & Lund (1995) are compared with the methods recommended in DNVGL-RP-F114 (2017). The calculated embedment from each method are compared for typical pipe properties and soil strength and discussed in view of field observations reported in the literature. The older methods were found to typically underestimate embedment for low shear strength profiles.

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