Study on Offloading Operation of Cylindrical FPSO Under Extreme Weather

With the wide application of cylindrical FPSO (Floating Production Storage and Offloading, FPSO), more and more people pay attention to its operational safety. To study and explore the safety of cylindrical FPSO offloading operation under extreme weather, it is necessary to conduct the simulation of whole operation process in such conditions. At first, the programming models are formulated for the cylindrical FPSO, shuttle tanker and tugs; then, based on the modelling, the responses of the cylindrical FPSO are simulated during offloading operation under various conditions, combined with Delphin Method and relevant theory. The most unfavorable load state and ultimate wind speed on unfavorable wind direction are explored through three stages: 1. changing the loading status of shuttle tanker and cylindrical FPSO; 2. changing the relative bearing of wind; 3. changing the wind speed. The results showed that when the offloading state is FPSO half-load & tanker half-load, it is the worst state to control the offloading system and the limit wind speed in the simulation is: cross wind ≤20 knots.By analyzing the motion response of cylindrical FPSO which is assisted by two tugs, a relatively objective and reasonable solution is obtained, which provides a beneficial reference for the future cylindrical FPSO offloading operation under the extreme weather conditions.