Liuhua 11–1 FPS, which named ‘Nanhai TiaoZhan’, is a major component of LH 11–1 oil field development. It was a modified drilling semi-submersible converted from a Sedco 700 series semi-submersible mobile offshore drilling unit (MODU) before 1995. The LH 11–1 field has been in production since 1995. The FPS had been already exceeding its original design life with serious plate corrosions and aging equipment in 2011. At the same time, a new oil field Liuhua 4–1 (OTC-24042), about 11 km away northwest LH 11–1, was in development planning with the utilization of LH 11–1 FPS facilities through a subsea tieback. Therefore, additional topsides capacities and the life extension of this aged semi-submersible FPS became necessary.
The original design life of LH11–1 was 10 years from 1995. The main objectives of this dry-docking upgrading project included a 15-year continuous service life extension, the resolution of existing corrosion issues on the FPS and the field development supports for LH 4–1 field. Details cover:
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Upgrade existing power system to meet the field development requirements.
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Repair, replacement or reinforcement of some pipes and structures of the FPS in order to extent its service life.
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Re-install and increase topsides equipment capabilities through repairs or the replacement of new ones.
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Improve the conditions of living quarters and the capacities of existing anti-pollution equipment for environmental protection purposes.
A well-planned and effective design, a good construction site implementation approach and a well-controlled progress management were the most important factors to achieve this project schedule target. In this paper, a detailed discussion of the designs and the refurbishment work of this FPS upgrading project with emphasis on technical and execution challenges and the measures taken during the project execution. This project provides a good example, on a real project with a tight schedule, for the upgrading and the life-extension of an aged deepwater floating production system.