Deepwater Mooring With High Stiffness Polyester and PEN Fiber Ropes

Abstract

The benefits of synthetic fiber ropes for deepwater station keeping are now well established and their use is expanding. Nearly all current applications use a single grade of polyester fiber, but for different supports and environments this may not be the optimal choice. Properties of polyester fibers can be modified by adjusting processing parameters and there are other fibers available such as PEN, which offer higher stiffness. This study examines the benefits of intermediate stiffness fibres, stiffer than standard polyester but less stiff than the high performance fibers. The results indicate that there is scope for improving mooring line performance and reducing line weight by careful evaluation of material options.

Development of Ultra-deep Water FPSO Mooring Ropes Using High Modulus/ High Tenacity Polyester Yarn

“…High modulus stiffer ropes are now required to reduce the platform (FPSO) offset in permanent moorings in water depth beyond 1500 meters (BOSMANN& HOOKER, 1999;DAVIES et al, 2008;STRESS, 2009;ROSSI, DEL VECCHIO& SILVA, 2009;ROSSI, DEL VEC-CHIO& GONSALVES, 2010). High modulus stiffer ropes are now required to reduce the platform (FPSO) offset in permanent moorings in water depth beyond 1500 meters (BOSMANN& HOOKER, 1999;DAVIES et al, 2008;STRESS, 2009;ROSSI, DEL VECCHIO& SILVA, 2009;ROSSI, DEL VEC-CHIO& GONSALVES, 2010).…”

“…Floating Production Storage and Offloading (FPSO) platforms will need permanent mooring using stiffer ropes and therefore will require a high modulus yarn in addition to the high tenacity required to make a lighter yet stiffer rope (BOSMANN& HOOKER, 1999;DAVIES et al, 2008;STRESS, 2009;ROSSI, DEL VECCHIO& SILVA, 2009;ROSSI, DEL VECCHIO& GONÇALVES, 2010). Petrobras (Brazilian national oil company) discovered in the last years large oil deposits in the Brazilian east coast offshore under a salt layer also known as "presal" or sub salt in water with depth exceeding 2000 meters with huge crude oil prod uction potential.…”

“…The goal was to develop a heavy denier High-Tenacity/ High-Modulus base yarn in order to produce mooring ropes that are stronger, stiffer (high modulus) and also lighter weight as compared with ropes based on yarn offering developed in the late 1990's with technology available at that time (BOSMANN, R. L. M., HOOKER, J., 1999;DAVIES et al, 2008;ROSSI, DEL VECCHIO, SILVA, 2009;ROSSI, DEL VECCHIO, GONSALVES, 2010).…”