Introduce Dissipation for Cylindrical Structures with Moon-Pool of Restricted Entrances

In order to consider the viscous effect,the introduction of a parametric dissipation and new results are realized by applying the new formulation combining and dynamic conditions over the free-surface with viscous terms. The dispersion equation is then modified by assuming an additional term in the boundary condition at the free-surface and wave-number becomes complex number with a small imaginary part which ensures the decay of wave amplitudes. The comparisons of numerical results and model test measurement on wave elevation at the moon-pool center is obtained both for the peak period and for the amplitude at resonance by choosing an appropriated dissipation coefficient. The results show that the introduce dissipation is not only effective but also reliable to provide realistic predictions.     

基于单井架钻机的月池区离线作业工艺分析

针对传统单井架海上钻井平台、钻探船作业时,无法同时完成其他并行辅助管线的连接、下放作业问题,提出了月池区离线作业思路,通过在月池区防喷器台车上加装可以提升、下放、悬持管线的动力装置,配合原钻机系统配套的猫道机、排管机、铁钻工等设备,实现在月池区接装、下放、悬持钻杆柱、套管柱及其他管串。使得海洋单井架钻井平台和钻探船在原井口进行正常钻井作业的同时,可以在月池区并行接装管串,实现并行作业,节省大量的钻井辅助作业时间,极大降低钻井成本。