Taut Mooring System Design and Analysis of Octagon FDPSO

Abstract

Abstract:

The existing mooring systems are compared and analyzed with the consideration of vessel shape, environmental condition and design cases. Average-distributed taut mooring system is finally selected for the octagon floating drilling, production, storage and off loading system (FDPSO) in the South China Sea. According to the requirements of station keeping and line forces, an averaged-distributed taut mooring system is designed based on the environmental condition at the depth of 2 000 m in the South China Sea. Compared with the traditional catenary mooring system designed for the same FDPSO, the averaged-distributed taut mooring system reduces the mooring system self-weight and the mooring radius on seabed. In addition, the offset of FDPSO with one mooring line damaged can be efficiently managed under 100-year environmental condition. The proposed mooring system can meet the requirements of octagon FDPSO. Furthermore, the research results will offer references for the mooring design of similar floating structures.

Key words: mooring system, floating drilling, production, storage and off loading system (FDPSO), taut mooring, catenary mooring

CLC Number:

U656.1+26

Qiang SUN, Qing-hui DONG, Gui-sheng PENG, Tian TIAN, Bin XIE, Shi-sheng WANG, Xi-chong YU, Jing-rui ZHAO. Taut Mooring System Design and Analysis of Octagon FDPSO[J]. Ocean Engineering Equipment and Technology, 2015, 2(3): 175-183.

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References 11

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状态	定义	偏移/m	受力安全系数
作业工况	一年一遇环境条件	100	1.67(锚链完整)/1.25(锚链破损)
生存工况	百年一遇环境条件	200	1.67(锚链完整)/1.25(锚链破损)

状态	水深/m	1 min平均风速/(m·s^-1)	表层流速 /(m·s^-1)	最大波高 /m	有义波高 /m	过零周期/s	谱峰周期/s	谱峰因子
作业	2 000	29.3	1.21	16.2	8.7	8.5	12.3	2.0
生存	2 000	46.5	1.60	28.0	15.0	10.4	15.1	2.4

状态	平均吃水 T/m	艉吃水 T_A/m	艏吃水 T_F/m	排水量 Δ/t	重心纵向位置X_g/m	重心横向位置Y_g/m	重心高 Z_g/m	横摇惯性半径R_r/m	纵摇惯性半径R_p/m	艏摇惯性半径R_y/m
满载	21.4	21.4	21.4	107 520	-0.17	0.37	24.07	29.52	29.57	35.05
压载	13.9	13.9	13.9	69 818	0.36	0.07	24.15	31.13	31.17	35.05

系泊线成分	链径/mm	长度/m	水中线密度/ (kg·m^-1)	刚度EA/MPa	破断力/kN	考虑12 mm腐蚀破断力/kN
上部R5无档链	162	80	329.62	1 640	26 100	23 000
GAMA 98?纤维缆	290	2 518	11.95	445	24 500	24 500
下部R5无档链	162	400	329.62	1 640	26 100	23 000

参数	定义	单位	数值
参数	定义	单位	上部锚链	中部系泊缆	下部锚链
C_D	拖曳力系数	-	2.4	1.2	2.4
ρ_growth	水生物附着密度	kg·m^-3	1 325	1 325	1 325
D	水动力直径	mm	162	290	162
t_growth	水生物厚度	mm	100	50	50
C_D	考虑水生物附着后拖曳力系数	-	5.4	1.6	3.9
D_G	考虑水生物后的水动力直径	mm	262	340	212