Model Test and Simulations of Split Mooring System for Congo LNG Project

Abstract The Congo LNG project, developed in the Republic of Congo, includes a pioneering advance in shallow water mooring systems. This project expands the storage capacity of the Tango FLNG by mooring the Excalibur FSU alongside it, enabling the accumulation of a marketable LNG export parcel. Unlike conventional designs, this project features a mooring system split between two vessels eliminating the needs for fenders and increasing the operability. The system also introduces interaction between all 12 degrees of freedom. These coupled modes present significant challenges in terms of hydrodynamics, which are addressed through a combination of model testing and advanced simulation methodologies. This paper presents a detailed analysis of the model tests conducted to validate the design and verify the simulation results that underpin class verification. The interaction between the connected vessels introduces new considerations for damping, excitation, and the overall dynamics of the system. The model tests provided invaluable insights into the intricate "dance" of the vessels, where all modes of motion are interlinked due to the unique mooring configuration. These tests not only demonstrated the system's performance but also helped assess the minimum clearance required between the vessels to ensure safe operations in the dynamic offshore environment. The data from these model tests were instrumental in calibrating numerical simulations, resulting in a more accurate representation of the physical phenomena involved. This calibration process was critical in ensuring that the theoretical models aligned with real-world conditions, thereby confirming the robustness of the design. The findings from the tests highlighted the importance of considering various damping and excitation mechanisms that were not as prominent in traditional designs. The results underscored the need for a sophisticated approach to model these effects, as they play a significant role in the overall performance of the FLNG system. By validating the design through rigorous model testing and subsequent numerical calibrations, the project not only achieved class verification but also contributed to a deeper understanding of the hydrodynamic interactions in complex offshore systems. The paper concludes with a discussion on the broader implications of these findings for future offshore projects, emphasizing the importance of integrated testing and simulation in the design process.