台风作用下锚泊定位半潜式钻井平台动力特性研究

南海台风活动频繁,严重影响着锚泊定位半潜式钻井平台的作业安全。采用水动力学计算软件 ANSYS-AQWA,基于三维势流理论和莫里森方程,建立了平台-锚泊系统耦合动力分析模型,开展了台风作用下的平台漂移分析和锚泊系统安全性评估。分析结果表明:当锚泊系统完整时,平台的平均漂移量与最大漂移量均超出API规定的许用值,需停止钻井作业并准备解脱,但锚链不会发生断裂。如果锚泊系统中安全系数最小的锚链发生断裂,平台的漂移量明显增大,锚泊系统最小安全系数明显减小,局部情况下锚链易相继断裂并造成连锁反应。研究表明,提出的相关方法和得出的结论可为极端天气下锚泊定位浮式装置的安全评估提供参考。 

The Dynamic Characteristics of Mooring Semi-Submersible Drilling Platform in Typhoon

Frequent typhoons in the South China Sea may significantly affect safety of the operations on semi-submersible drilling platforms with anchor mooring system. By useing hydrodynamic calculation software, ANSYS-AQWA, the coupled dynamic analysis model for the platform-mooring system was established, and an analysis on the drift of semi-submersible platforms and the safety assessment of anchoring system were conducted based on three dimensional potential flow theory and Morison equation. The analysis results showed that when the mooring system was intact, both the average and maximum drift distances of platforms exceeded the allowable values specified in API. Under such circumstances, drilling operations should be suspended and a disconnection between the drilling riser and the wellhead should be done, if the anchor chain does not part. when the anchor chain of the least safety factor in the mooring system parted, the drift distance increased significantly, the minimum safety factor of the mooring system decreased obviously and in some cases, other anchor chains then parted in succession, leading to chain reactions. Research results showed that the proposed methods and the obtained conclusions could provide a reference for security assessment of mooring floating structures in extreme weather conditions.