A Variable Static-dynamic Polyester Stiffness Method for SEMI Mooring System Design and Global Sensitivity Parameters Analysis

摘要

The aim of this paper was to examine the design of the polyestermooring system of deep draft SEMI in one project in the northernSouth China Sea. This is the first deep water permanent polyestermooring project in the South China Sea.This paper compare two commonly used polyester models, the upperlowerbound stiffness model and static-dynamic stiffness model. Thebetter method was determined by simulating the real stiffness ofpolyester through the comparison study. Then we use the preferredmethod for the design of polyester mooring system in the deepwater inthe northern South China Sea.Mooring analysis is conducted for the Semi platform with theconsideration of conditional seastates for operating cases. Analysiscovers mooring lines intact and 1-line damaged conditions for bothInitial and all Future Riser configurations. Screening analysis was firstconducted. The critical case sensitivity checks were also performed.Wave period sensitivity and environment direction sensitivity (+/-10°)is applied under the selected critical condition from the maximum windcase. In addition, as wave dominant cases are more sensitive to theperiod change, the sensitivity on wave period (Tp+/-0.5s and Tp+/-1.0s)is also studied under the maximum wave condition.