深水顶部张紧钻井隔水管非线性静力分析

Nonlinear static analysis of top tensioned drilling riser in deepwater

用ABAQUS软件对用于1500m水深的顶部张紧钻井隔水管进行了非线性静力分析。定量分析了钻井船平均偏移、张力比、海流剖面对深水钻井隔水管弯矩、横向变形、应力水平和底部球铰转角的影响。增加张力比,可显著减小隔水管弯矩、隔水管底部球铰转角以及隔水管的横向变形;但是增加张力比同时会增加隔水管的应力水平,这就要求张力器能够提供更充足的顶部张紧力。钻井船平均偏移对隔水管弯矩和隔水管底部球铰转角有明显影响,控制钻井船平均偏移对于保证海洋钻井的顺利进行具有重要意义。海流是深水钻井重要影响因素之一,海流对隔水管弯矩分布、隔水管中下部的受力状况甚至隔水管的整个作业过程均有显著影响。应加强对海流数据的监测,将海流对深水钻井隔水管作业过程的影响降至最低。

In this study, a top tensioned drilling riser in water depth of 1500m is analyzed statically using ABAQUS solver. A quantitative analysis is carried out to determine the effect of vessel mean offset, top tension ratio （TTR） and current profile on the deepwater riser bending moment, lateral displacement, stress level and lower flex-joint angle. The results show that the increase of the TTR will lead to the reduction of bending moment, lower flex joint angle and lateral displacement of the riser considerably. However, the stress level of the riser increases significantly with the increase of TTR, which requires that the tensioner is capable of providing sufficient top tension. Vessel mean offset has significant effect on bending moment and lower flex joint angle, which should be controlled to ensure the deepwater drilling operation. Current is the major factor influencing deepwater drilling, which has significant effect on bending stress, lower part mechanical state, and the whole operation procedure of the riser. The effect of current on the riser should be minimized by strengthening the monitoring of current.