Model Testing the 3D Dynamic Behaviour of the GAP System and Comparison With Numerical Computations

MURPHY Sabah Oil Co. Ltd. is developing the Kikeh Field located offshore Malaysia in the South China Sea in a water depth of 1325m. This field development is based on a Floating Production Storage and Offloading unit (FPSO) and a wellhead Spar Dry Tree Unit (DTU). Fluids will be transported in fluid transfer lines (FTL) using SBM’s newly developed and patented Gravity Actuated Pipe (GAP) system to support a horizontal neutrally buoyant bundle of flow lines between two moored floaters. Fatigue and extreme analyses of the GAP system have been carried out with a fully dynamic numerical model. In order to verify the validity of the model, three dimensional tests have been performed by OCEANIDE in IFREMER basin in Brest (France). The complete GAP system was modelled at 1:37 scale by OCEANIDE (France). The model included the GAP bundle (carrier pipe with four flow-lines and one umbilical), two towheads located at each extremity of the bundle, a tether chain arrangement supporting the GAP bundle at its two attachments on the FPSO and the DTU. The paper will cover the salient results of the model test campaign. A comparison between tests-results and numerical simulations will also be presented. Furthermore, the occurrence of such dynamical behaviours as Heave Induced Lateral Motion (HILM) will be investigated.