Design And Analysis For Taut Mooring System Of Deepwater Floating Platform

Deep water Floating Production platform(FPS-Floating Production System)is a semi-submersible platform with functions of deep-sea oil and gas drilling,production,storage and transportation.FPS in the case of ultra-deep-water operations,often uses taut mooring system to locate.Taut mooring system because of its anchor chain using polyester fiber cable and other new materials,light weight and strength,is more suitable for deep-water operations.In recent years,it has been widely used.At present,although there are specialized fiber cable design specifications,but more for the concept and related standards,the lack of detailed design process,in addition,the tension of the mooring system static stress strain relationship and nonlinear problems of study is very limited.Based on a FPS as an example,this paper studies taut mooring system design method,the main contents are as follows:(1)According to the characteristics of the taut mooring system,the relevant requirements in the API rules are studied,the existing engineering experience are used.A design method suitable for tensioning mooring system is proposed,and the design process is determined.the research gives the design process:Firstly,the mooring scheme is designed,analyzed and checked,and then the mooring parameters are optimized and the optimal design is finally selected to evaluate and analyze.According to the design method of the mooring system,the mooring scheme is designed and perfected for the target platform.(2)Based on the traditional catenary theory and the stress-strain relation of the fiber cable,the static equilibrium equation of the nonlinear mooring cable is established,the corresponding program is written and an example verification is made.The rationality of the preliminary design of the mooring scheme is examined,and the optimal well layout orientation of the target platform is further studied,which provides the reference for the later dynamic analysis.(3)The method of static analysis,frequency-domain hydrodynamic analysis,time-domain coupling analysis and nonlinear coupling analysis is used to analyze the method of dynamic response and tension characteristics of taut mooring and floating platform.The mooring design scheme was evaluated.(4)The influence of parameters such as pre-tension size,the inclination angle of pre-tension,the angle of mooring lines,the number of mooring lines and the position of the guide hole is analyzed.The mooring design scheme is optimized,the final scheme is calculated and the results are analyzed.