Dynamic Responses of FPSO

Floating Production Storage and Offloading (FPSO) is a vessel that are currently in
demand all over the world in which it is operated in a deep water region. Fixed
platforms such as the bottom-supported steel jackets and concrete platforms are said
to be impractical in the economic point of view which pipelines need to be installed
along the seabed which is very costly especially in the deep water areas. Most
floating production units is a buoyant structure which allows six degree of motion in
surge, heave, pitch, yaw, sway, and roll. This floating structure is able to rotate freely
in response to harsh environment and the mooring system used is disconnectable
from the FPSO so that it can be protected from natural disaster such as Hurricane
and Katrina. The need to possess a study on this floating structure on the dynamic
responses due to environmental load is essential for excellent operation in the deep
water areas. The dimension of FPSO is taken from FPSO Berantai project whereas
the environmental data conditions were taken from the Petronas Technical Standards
(PTS) for operating condition which consist of wave height, period, wind and current
speed. FPSO is modelled as a floating structure with three degrees of motion: surge,
heave and pitch motion. Since FPSO is a very large structure, the excitation of wave
forces acting on this floating structure is calculated by using the Froude-Krylov
Theory. This theory utilizes the incident wave pressure and pressure-area method on
large surface to determine the forces. The ship’s behavior and motion is studied by
using Response Amplitude Operator (RAO) to determine the sea state when there is
a ship move along the water. Frequency Domain Analysis was used to conduct
hydrodynamic analysis in order to determine the floating platform motion in surge,
heave and pitch motion in regular and random wave. The energy distribution on sea
is represented using frequency domain analysis and wave motion profile was
generated using P-M wave spectrum. In a conclusion, it is vital to determine the
motion on each direction to ensure the safety of the FPSO and maintain the operation
in the most ideal and stabilize condition.