Study on A New Concept of Offloading System for SDPSO Available to Purchase

SDPSO platform is a deep-draft floating platform integrating the critical functions of drilling, dry-tree production, oil storage, and offloading capabilities, and improves the flexibility of the technical solution and reduces the overall cost of deepwater oil field development. Most of FPSOs in the world, which are vessel-shaped and moored by single-point mooring systems, can be positioned weathervane. Their offload tankers are moored by tandem or side-by-side method, which allow the tanker to be rotated around the single point with the FPSO. SDPSO is positioned by a spread mooring, so the tandem or side-by-side mooring pattern cannot be used, because it may lead to a collision between tanker and FPSO. There are two feasible options. One is using a dynamic position tanker to offload oil, and the other is adding a CALM buoy between FPSO and tanker. Both two options are high costs, so it is significant to develop a new low-cost offloading method or system. This paper proposed a ring mooring system for a shuttle tanker to offload oil from SDPSO. The ring mooring offloading system (RMOS) can allow the tanker to be rotated around SPAR under the environment loads. Meanwhile, a smart setup of the floating hose is applied to avoid using an expensive oil transfer swivel. Besides, numerical analyses are performed to demonstrate the performance of this concept. Numerical simulations were conducted using a fully coupled nonlinear time-domain analysis. The distance between the shuttle tanker and the SDPSO is optimized based on the relative motions of the two floaters and the hawser tension requirement of the shuttle tanker. The ring mooring system demonstrates robust performance and cost-effectiveness for the SDPSO.