Integrating hydrodynamic and nautical studies for offshore LNG operations
Author Arjan Voogt, Jaap de Wilde and Johan Dekker
Title Integrating hydrodynamic and nautical studies for offshore LNG operations
Conference/Journal OTC
Paper no. 25383
Month May
Year 2014

For offshore LNG production, the ability to safely offload LNG to shuttle carriers is an important driver in the design. Hydrodynamic studies and nautical studies can be used to select an offloading concept, optimize the operational procedure and evaluate the terminal availability. These studies involve mariners and mathematics. Full mission bridge simulators are traditionally used to train for the operation and to evaluate its feasibility. By incorporating state-of-the-art hydrodynamic models, the full mission bridge simulator can also be used for concept engineering. This allows a bridge between design and operation. It provides feedback from the operation into the design and improves operational guidance. This paper shows examples of this approach, while evaluating both tandem and side-by-side offloading.
With hydrodynamic studies the relative motions and mooring loads between the permanently moored vessel and the transport vessel are estimated. This paper concludes that 97% weather uptime can be achieved in waves with up to 3 meters significant height for side-by-side while the same uptime can be achieved in waves up to 5 meters for dynamic positioned tandem offloading. Tandem offloading is often perceived as a safer option than side-by-side offloading, due to the larger distance between the vessels. Although the tandem configuration seems more promising for offshore offloading, it requires new technology for LNG transfer, which is why it has not yet been applied. Integrating hydrodynamic and nautical studies can help to evaluate cryogenic hose handling and tug operations during the final phase of the approach and departure of the LNG carrier.

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