Seismic Design of Hebron Platform: An Integrated Soil-Structure-Interaction Approach

Seismic analysis of an offshore platform requires an integral model combining all its elements: foundation, substructure, deck, modules, appurtenances, and even pipeline and riser tie-ins. With typical breakdown of project scope amongst several EPC contractors, the task of creating a seismic model and ensuring proper input, output and updates for EPC contractors’ design always rests with the operator’s engineering team. This model is complicated by the nature of dynamic soil-structure-interaction characterized by radiation of earthquake wave and energy to the far field. This radiation of energy is significant for short squatty gravity-base structures while most structural software lack this capability. This problem has been worked by the nuclear industry, but in this paper we summarize ExxonMobil practice for carrying this task in this scope breakdown environment. The need for this practice emerged during the engineering of Orlan (Sakhalin), was first used on the Adriatic LNG Terminal (Italy) and applied since on Berkut (Sakhalin) and Hebron (Canada).