深水钻井隔水管悬挂窗口确定方法

Determination of the hang-off window for deepwater drilling riser

隔水管悬挂窗口为允许隔水管进行悬挂作业的环境载荷极值条件,钻前形成悬挂窗口对于指导隔水管现场作业至关重要。提出隔水管软、硬悬挂模式作业窗口分析方法,建立隔水管轴向动力分析有限元模型,基于隔水管悬挂作业限制准则,进行不同海况条件下的隔水管悬挂窗口研究。波高周期作业窗口分析表明,隔水管硬悬挂窗口受平台升沉运动与波浪周期共同影响,波浪周期在10～16s、20～24s之间的作业窗口较窄,硬悬挂自存时推荐平台艏向取45°浪向角;隔水管软悬挂窗口主要受伸缩节冲程限制,不同浪向角下的作业窗口基本相同。波浪海流作业窗口分析表明,海流流速越大隔水管悬挂允许的最大波高越小。对比两种悬挂模式下的作业窗口,软悬挂模式较大地扩展了隔水管的悬挂作业窗口。

The riser hang-off window is an extremum condition of environmental load to allow the riser hang-off operation,which is essential to the field operation.Here we put forward a method to analyze operating windows for soft or hard hang-off modes of the riser,which includes to establish a finite-element model for the riser axial dynamic analysis and to examine riser hang-off windows under different oceanic conditions based on the restraint criterion of riser hang-off operations.Analyses of operating windows of wave height and periods show that the hard hang-off window is jointly affected by the vessel heave movement and wave periods,and it gets narrower when the wave period falls into a range of 10～16s or 20～24s.The recommended vessel heading for the hard hang-off mode survival in case of extreme weather should be at a 45° wave direction angle.The soft hang-off window is restricted mainly by the telescopic joint stroke and it keeps approximately identical,independent of the wave direction angle.Analyses of operating windows of wave and oceanic current indicate that the maximum allowable wave height for the riser hang-off operation gets smaller when the oceanic current velocity increases.A comparison of operating windows between the two hang-off modes shows that the soft hang-off mode can significantly expand the riser hang-off operating window.