Preparation and Execution of the GAP Surface Tow

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. This paper highlights the challenges and solutions associated with the engineering and execution of the 188 nautical mile tow of the GAP from the SBM construction site in Bintulu (Malaysia) to the Kikeh Field. Substantial effort was invested at the engineering stage to study the tow-induced fatigue, including influence of wave direction, tow speed, trailing tug back tension, current and submergence of towheads in order to develop a tow strategy which was a compromise between fatigue damage reduction and realistic and cost effective marine operations. This process is detailed in the paper. Finally, all tasks associated with tow from the point at which the beach hold-back rigging was abandoned to the point at which field pre-entry tasks were carried out are also described in the paper.