In-Place Strength Evaluation of Existing Fixed Offshore Platform Located in Persian Gulf with Consideration of Soil-Pile Interactions

Offshore jacket structures have been used in petroleum industry for decades. Due to increasing the age of operating platforms, structural damages will be generated by corrosion, fatigue, ship impacts and other reasons. Improvements in the oil and gas recovery from several fields have raised the interest for using these platforms well beyond their intended design life. Life extension of an existing jacket platform needs proper reassessment of its structural members, such as piled foundations. This paper represents a case study of the existing fixed offshore platform located in Persian Gulf by in-place strength analysis. The objectives of this analysis are to verify whether the platform can meet the structural requirements, as per API RP 2A and AISC, for the In-place extreme met-ocean loading. The structural assessment is performed based on the best estimates of the existing conditions of the structure data on the future corrosion allowance. Since the response of the jacket platform to the environmental loads is intensely affected by the pile soil interaction, in current study the foundation is modelled using uncoupled non-linear soil springs acting along the piles length. The load cases, which include all situations relevant in the In-place analyses are taken into account. Results of the In-place analysis of the drilling platform indicate that the jacket structure does not assure the code provisions.