Coupled Analysis of an FPSO and Dry Tree Unit Connected by a Gravity Actuated Pipe (GAP)

MURPHY Sabah Oil Co. Ltd. has developed 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 Spar Dry Tree Unit (DTU). Fluids are transported in fluid transfer lines (FTL) using SBM’s newly developed and patented Gravity Actuated Pipe (GAP) system. To our knowledge this is the first time two large moored floaters are connected together by a slender body closing a gap of 1600m. It was not clear at the beginning of the project to what extent the first and second order motions of the two floaters were coupled, if at all, owing to the presence of the GAP system. To investigate the extent of coupling, both frequency domain (modal analysis) and time domain analyses of the FPSO, GAP system and Dry Tree Unit were performed. The salient features and results are presented.