Availability assessment of a monobuoy-anchored ship to ship offloading system. (August 2020)

• Record Type: Journal Article
• Authors: Vieira, D.P.; Tannuri, E.A.; Câmara, J.G.A.
• Is Part Of: Applied ocean research. Volume 101(2020)
• Publication Date: 2020-08
• Subjects: Ship to ship -- Offloading operations -- Coupled hydrodynamics -- Single point mooring; Ocean engineering -- Periodicals; 620.416205
• DOI: 10.1016/j.apor.2020.102291
• Languages: English
• ISSNs: 0141-1187

Abstract

Highlights: Ship to ship transshipment operation using a monobuoy as a single point mooring system is studied. The system heading is evaluated considering wind, current and waves forces and moments. The efforts in the monobuoy mooring system are calculated employing a quasi-static approach. A linearized dynamic model is adopted to assess the tensions in lines between ships. System availability is obtained using a series of 10-year environmental conditions. Abstract: Cargo transshipment operations between large vessels are increasingly recurrent in the oil and gas industry scenario. Due to the operational limitations of Brazilian terminals and ports and recent discoveries of large oil and gas offshore fields in the pre-salt area, new types of configurations are being studied to propose alternatives for operators. The present work proposes a methodology for the analysis of the availability of a ship to ship offloading operation using a monobuoy single point mooring system. The study initially contemplates a quasi-static analysis considering a 10-year history of measurements of environmental conditions such as wind, current, wave, and swell, which to obtain the system heading, loads on the monobuoy, and static tensions in the mooring system between ships. In sequence, the dynamic tensions are calculated as a function of the first-order relative movements caused by the wave and swell incidence. Also, it is proposed to use a tugboat to align the system with the waves' incidence angle in order to reduce motions and increase availability, which is confirmed by the obtained results. Furthermore, the system's performance is assessed according to the variation of loading conditions, the relative positioning of the vessels, and different operating scenarios.