摘要
为评估水下井口下沉时送入管柱在瞬态动力和纵向振动下的安全性,基于动力学及振动力学,建立了深水送入管柱的物理模型,分析了水下井口下沉瞬间送入管柱的应力变化以及平台起伏垂荡对送入管柱纵向振动的响应。结合南海某区域的工程数据,利用有限元软件,对不同长度、不同下端悬挂质量的送入管柱进行了分析。分析结果表明:送入管柱的长度和下端悬挂质量是影响送入管柱固有频率的主要因素,送入管柱越长,下端提起的质量越大,相应的固有频率越小;半潜式平台垂荡的频率范围主要处于送入管柱第1阶频率附近,送入管柱存在共振的可能性;以平台垂荡振幅功率谱对送入管柱进行随机振动分析得到振动载荷50〜200 kN,通常不会立刻造成送入管柱失效,但长期则会造成疲劳损伤,因此应尽可能在风平浪静的环境下作业;水下井口下沉时,送入管柱瞬态的动应力达到最大值,为静应力的1.4〜1.5倍,对送入管柱的安全性影响显著,因此在设计阶段要选用满足瞬态动力的送入管柱,保证其在危险工况下不失效。所得结论能够为深水送入管柱设计、作业,以及水下井口下沉事故处理提供参考。
In order to evaluate the safety of the running string under transient dynamic stress and longitudinal vibration at the time of sinking of subsea wellhead,based on dynamics and vibration mechanics,the physical model of the running string in deep water was built,and the stress change of the running string at the moment of sinking of subsea wellhead as well as the response of the platform heaving to the longitudinal vibration of the running string were analyzed.Combined with the engineering data of a certain area in the South China Sea,the finite element software was used to analyze the running string with different lengths and different suspended mass at its bottom.The study results show that the length and suspended mass at bottom of the running string are the main factors affecting the inherent frequency of the running string,the longer the running string,the greater the suspended mass at its bottom,the smaller the corresponding inherent frequency is;the frequency range of heaving of semi-submerged platform is mainly near the first-order frequency of the running string,and the running string has the possibility of resonance;the random vibration analysis of the running string carried out using the heaving amplitude power spectrum of the platform shows a 50~200 kN vibration load,which usually does not immediately cause the failure of the running string,but it will cause fatigue damage in a long term,so operation should be carried out as far as possible in a waveless environment;when the subsea wellhead sinks,the transient dynamic stress of the running string reaches the maximum value,which is 1.4~1.5 times of the static stress,and has a significant influence on the safety of the running string,so in the design stage,the running string meeting the transient dynamic stress should be selected to ensure that it does not fail under dangerous working conditions.The conclusions are of reference significance for the design and operation of the running string in deep water and the sinking accident treatment of subsea wellhe
作者
焦金刚
谢仁军
吴怡
Jiao Jingang;Xie Renjun;Wu Yi(CNOOC Research Institute Co.,Ltd.,State Key Laboratory of Offshore Oil Exploitation)
出处
《石油机械》
北大核心
2021年第12期62-69,共8页
China Petroleum Machinery
基金
国家科技部项目“海上试验及工程应用示范总体方案优化设计”(2017YFC0804509-001)
中国海油科技项目“深水开发井不同开发模式下的钻完井方式研究”(2018KJ-ZC04)。
关键词
深水
送入管柱
水下井口下沉
平台升沉
平台垂荡
纵向振动
deep water
running string
sinking of subsea wellhead
platform heaving
longitudinal vibration
