Insights On Suction Pile Offshore Installation in West African Deep Water Field

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Suction piles have been widely used in oil & gas industry for several decades. The present paper provides feedback on the design and installation of six suction piles installed in West African deep-water field. Three suction piles were used as restraining piles for flexible risers and were submitted to a horizontal load reaching 50 T. The last three suction piles were used as Manifolds foundations and were submitted to high compressive loading reaching 350 T. For this field, piles outer diameter was standardized and fixed to 4.9 m for manufacturing issues, whereas penetration depths ranged between 11 m and 20 m below seabed. In this project, typical aspect ratios ranging from 2 to 4 were used. Water depth in the field ranges between 800 and 1300 m and soil conditions are soft to firm clay with some intermittent silt layers in specific locations. A specific challenge of the field is the high seabed slopes in certain locations near channel areas. Three restrain piles were installed where the seabed slope ranged between 7 and 9 degrees. This paper summarizes the methodologies followed for suction pile design in terms of stability, installation, extraction and settlement analyses based on API recommendations. It provides also a useful and considerable feedback of suction piles behaviour during offshore installation. Indeed, measured and predicted self-weight penetrations and required suction pressures are compared, analysed and discussed in order to check design assumptions and improve design methodologies for future projects in similar soil conditions.

5th International Symposium on Frontiers in Offshore Geotechnics (ISFOG2025)

11 - Suction installed foundations and anchors