Semisubmersible Floating Production System (Semi-FPS) with Steel Catenary Risers (SCRs) is an attractive field development solution worldwide, and especially so in deeper water of Western Australia. However, SCR design is challenging in the offshore Western Australia environment due to severe cyclonic environments and persistent swells.
This paper presents a comparison of three different field development alternatives that use Semi-FPS with SCRs in deepwater Western Australia. These alternative solutions are conventional semisubmersible hull design with Steel Lazy Wave Riser (SLWR), deep draft semisubmersible hull design with conventional SCRs and a novel semisubmersible hull design with conventional SCRs.
The study considers a typical wet tree development for a gas field with a new build Semi-FPS host facility in 4,000 ft (1,220 m) water depth. 10-inch production and 16-inch export SCRs are considered in this study. Feasible riser designs are developed for each alternative solution.
Numerical results are presented to compare the performance of the three hull designs. Project Execution Plan (PEP) and the identified risks and risk mitigations associated with the novel hull design have been addressed in this paper.
Finally, differences in the hull, mooring and SCR total installed cost (TIC) as well as project execution schedule for the three alternative solutions are summarized and presented. The paper concludes with a comparison of the three Semi-FPS hull- riser choices along with a summary of the relative benefits and risks.
