Hydrodynamic Responses and Loads of a Model Floating Hydrocarbon Storage Tank System for Concept Validation and Numerical Verification

Abstract

An innovative floating hydrocarbon storage facility (FHSF) has been proposed to utilize the shielded near-shore area for countries with large demand on the land space such as Singapore and Japan. The concept comprises 14 floating hydrocarbon storage tanks (FHST) and several surrounding floating barges. All the modular designed FHSTs are loosely connected to the barges through a soft mooring system so as to reduce the loads, and the entire system is free to float to reduce the tidal influence. The single FSHT has been proven to have moderate hydrodynamic responses in previous studies, but there still exist concerns on the influence of potential resonances in the narrow gaps and the strong hydrodynamic interactions. The loads on the specially designed soft mooring system have to be checked. The complete system is complex and difficult to analyze. So, experimental studies were performed on both a simplified system and the complete system to ensure the quality and reduce the uncertainty in the experiments. The simplified system consists of two FHSTs and a surrounding floating barge frame. The experiments were performed in the ocean basin in SINTEF Ocean. A series of random, wide-band and realistic random wave tests were carried out to generate benchmark data to verify numerical analysis tools. This paper will focus on this simplified system that represents the complete system’s behavior. A frequency domain numerical model of the simplified system was established based on potential theory. Empirical coefficients were used to account for viscous damping. The numerical results are comparable to the experimental results in general. The statistical responses of the FHST in the design sea states are also within the acceptable range even with the hydrodynamic interactions. However, further improvement on the system such as a better design of the floating barge is necessary.