The present paper studies numerically and experimentally hydrodynamic responses of a moored four columns semi-submersible with/without presence of another TLP shaped floating structure in regular waves. The six degree of freedom motions of the model moored on springs measured by the optical tracking system (Qualisys Camera) that captures the positions of the reflective optical tracking markers placed on the model. In numerical study, hydrodynamic problems are investigated by using HydroStar which is based on three-dimensional source distribution method, within the scope of linear wave theory and using frequency domain.

In recent years, the applications of floating platforms are going to be widespread with the exploration of oil and gas resources. They have moved to further than 2000m water depth and target the 3000m range. Unlike seagoing ships, moored floating offshore structures such as semisubmersibles and TLP are usually positioned at a given location at sea and their motion is externally constrained by the moorings. Motion response of a floating structure should be kept adequately low to guarantee the safety of risers and umbilical pipes as most important components in the equipment of oil production. The less amounts of motion the more safe operation is.

The experiment was conducted under condition as follows: time peak period (Tp) 1.85 – 2.15 second and significant (Hs) wave height 7.29 – 10 cm. Surge, heave and pitch response amplitude operation (RAO) of moored semisubmersible at different wave frequencies were plotted. Then the RAOs plotted for semisubmersible leeward of the other moored structure. The results of the floating structure interaction in surge, heave, and pitch motion were discussed and showed presence of TLP affect the motion responses of Semisubmersible in all directions.

This paper: Investigating the feasibility of installing two floating structures beside each other in deep water; evaluating the interaction effect on floating structure; evaluating amount of Response Amplitude of Operation.

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