深水钻井隔水管与井口耦合作用力学仿真分析

Mechanical simulation analysis of coupling action of riser and wellhead in deepwater drilling

深水钻井时由于海底情况复杂,井口系统的稳定性可能受到诸多因素的影响。本文结合实际工况,综合考虑浪流载荷和地基反力等因素,建立了深水钻井系统力学理论模型,并分析了张紧力和平台偏移量对隔水管和地层组合管柱力学行为的影响规律。分析结果表明:上部载荷对地层管柱作用都集中在管柱的上部较短区域,作用能力有限;增加张紧力可以减小隔水管的横向位移和截面弯矩,有利于隔水管的稳定,但是会增加地层组合管柱的横向位移和弯矩,增加井口装置倾覆的风险;过大的平台偏移量会导致全段管柱较大的横向位移和截面弯矩,使得管柱被破坏的可能性大幅度增加。所以在钻井作业时,有必要控制平台偏移量,取用合适的张紧力,保证作业安全。

In deepwater drilling, the stability of wellhead system may be affected by many factors due to the complexity of seabed condition. In this paper, considering the subgrade reaction and wave flow, mechanical model of deepwater drilling system is established combined with the actual working condition, and the effects of the tension and platform offset column on the mechanical behavior of riser and strata combination has been analyzed. The analysis results show that the upper load to the stratigraphic combined pipe is concentrated in the upper part of the pipe, and its function is limited. Increasing the tension can reduce the lateral displacement of the riser and the bending moment of the section of riser, and it is beneficial to the stability of the riser. However, it will increase lateral displacement and bending moment of stratigraphic combined pipe, and increase the risk of damage to wellhead equipment. Large platform offset will lead to larger lateral displacement and bending moment of the hole pipe, and increase the risk of pipe damage. Therefore, it is necessary to control the offset of the platform and take the proper top tension to ensure the safety of the operation during drilling operation.