Design and Analyses of 343K DWT FPSO for GIRASSOL Field

Abstract

Abstract This paper presents the design and analysis of a new building FPSO with 343K DWT capacities. The FPSO is installed at the benign Girassol field offshore of Angola. The water depth at the Girassol field is 1,350m. During the project, hull design, detailed hydrodynamic, structural and fatigue analyses have been performed. This paper describes the general analyses methods used and presents some typical results from the analyses carried out by FPSO Builder. Through the project, the FPSO Builder has established a new standard for effectively designing and constructing FPSO's to cope with the increasing demands of large FPSO's in deep waters. The experiences and technique obtained during the design and analysis of the Girassol FPSO will be the references for the future builder of the FPSO's in deep and benign waters. Introduction This paper describes the overall design and analysis procedures in relation with the new building of the FPSO with 343K DWT capacities. The FPSO is installed at the benign Girassol field, which is located about 210 kilometers NNW of Luanda, Angola. The water depth at the Girassol field is 1,350m. During the project, hull design, detailed hydrodynamic, structural and fatigue analyses have been performed. In contrast to general ships, the hull of Girassol FPSO has been designed based on direct calculation of wave loads, stochastic fatigue analysis and impact analysis for enhanced safety and reliability of the vessel. Especially, extensive fatigue analysis has been performed to ensure the structural safety in connection with hull-related members, topside support stools, flare support stools, riser supports, etc. This paper describes the general analyses methods used and presents some typical results from the analyses carried out by FPSO Builder. Through the project, the FPSO Builder has established a new standard for effectively designing and constructing FPSO's to cope with the increasing demands of large capacity FPSO's in deep waters. The experiences and technologies obtained during the design and analysis of the Girassol FPSO will be the important references for the future work of the FPSO's in deep and benign waters. General Arrangement & Specifications The hull of the FPSO has an overall length of 300m, a molded breadth of 59.6m, a molded depth of 30.5m and a design draught of 22.77m. The FPSO is able to store two million barrels of crude oil and support process facilities with a capacity of 200,000 barrels per day. Deadweight is 343,000 ton, which includes 98% of cargo capacity and 50% of slop tanks. The design life of the hull is 20 years without drydocking with factor of 2 for fatigue design life. The hull features a double-sided construction with 12 ballast wing tanks measuring 7m wide, as well as two fore-peak and two aft-peak ballast tanks. The FPSO has 12 oil storage cargo tanks. The topside deck is 180m long and 60m wide. It weighs approximately 20,000 ton and includes living quarters, oil and gas treatment equipment, storage and offloading equipment, and re-injection facilities.