Computer Aided Design of Semi-submersible for Deepwater Operations

In PETRONAS, there is no known design library of offshore floaters thus extensive
iterative process is typically being engaged for concept design and selection work.
Determination of specific parameters with respect to scaled model testing and calibration
is not always straightforward, and involves cross referencing between numerical analysis
and experimental testing. Hence, the objectives of the project are to develop semisubmersible’s
hull section to eliminate some of the iteration in concept design and
selection work by initiating a semi-submersible computer aided design (CAD) model
library for future design selection work and to evaluate the stability of three different
values of waterplane area of column of a semi-submersible CAD model at operating
condition at the same water depth. The scope of the study is to focus on developing the
hull section of a four-column ring pontoon semi-submersible production platform model
using CATIA V5R12, the chosen parameter that will be varied is the waterplane area of
the column under fixed design specifications and the semi-submersible’s stability will be
analyze by vertical center of gravity and draft. The design library was achieved through
literature review, calculation, part design and assembly design for CAD model
development, application of parameters and formula function and analysis and data
generation. The expected results would be three sets of semi-submersible’s hull CAD
model that differ in waterplane area of column with automated selected parameters
computation and an analysis on the relation of the waterplane area of column with draft
and vertical center of gravity of each model. As a conclusion, the three CAD models of
four-column ring pontoon semi-submersible’s hull and the analysis are the initiator for
the offshore floaters design library which eliminates some of the iteration in conceptual
design stage for future design selection work and the increment of waterplane area of
column increases vertical center of gravity and reduces draft. Both conditions increased
the probability of the semi-submersible to be flooded.