TARPON MONOPOD MARGINAL FIELD STRUCTURE SUBJECTED TO SEISMIC GROUND ACCELERATION

For seismically active areas it is preferred that the intensity and characteristics of seismic ground motion used for design be determined by a site specific study. Since Malaysia is not located within seismically sensitive zone, seismic ground acceleration tends to be neglected from dynamic load design of offshore structures within the region. However, it is reported that tremors have been occurring and felt by platform operators in Malaysian Water. As Tarpon Offshore Platform is relatively contemporary within PETRONAS assets in Malaysia, there are no available specific tarpon inspection requirements or maintenance guidelines. Platform robustness and integrity cannot be ascertained. In regards to recent study of PSHA which is carried out by site-specific study, it is obtained that the mean hazard predicted is somewhat higher than of seismic model published by other studies, as well as API benchmark for evaluation of seismic activity to an offshore structure for a particular region. In this paper, the platform response towards seismic ground acceleration is investigated. By taking extreme condition of environmental loads and suggested ground acceleration values, the author will define the threshold unit at which ground acceleration is possibly controls the overall performance of a marginal field platform. In conjunction with that, platform natural behaviour and ultimate resisting force is identified in order to evaluate the platform integrity hence verify the latter findings.