Parametric Study of Spar Platform Responses

Since the first spar platform was installed in Gulf of Mexico (GOM) in 1996,
spar platform has been regarded as competitive floating structure for deep-sea oil
exploration. In this study, dynamic analysis is applied to measure the responses of a
typical spar platform in order to measure instantaneous amplitude and frequency
fluctuations of three degrees freedom (surge, heave and pitch). The analysis was
performed for a spar subjected to random wave loading represent an operational
condition of 100-year storm in Gulf of Mexico. The first part of this project focuses
on the detailed information of the chosen existing spar. Next, the evaluation of the
responses using mathematical calculations and it is modeled as a rigid body
connected to the sea floor by multi component catenaries mooring lines. Frequency
domain analysis has been performed by choosing P-M Spectrum model to represent
an appropriate density distribution of seawater at the site under consideration. The
parameters chosen for assessing the responses are the stiffness that varies t 10% of
original stiffness and different condition of hydrodynamic coefficients (Clean and
Fouled). From the analysis, the response increases when the stiffness was lower and
decreased when the stiffness is higher than the original. The smaller value of
hydrodynamic coefficient affects the spar motion by decreasing it. The results
presented in this paper will provide an insight to the differences in Spar motion
responses due to the variation in both design parameters. The findings should be
beneficial for spar design in an early project stage.