波动钻压下阶梯钻柱系统稳定性研究

发布时间：2018-05-09 13:19

本文选题：阶梯钻柱 + 输液管　；参考：《固体力学学报》2017年03期

【摘要】：处于狭长井筒中的钻柱,其动力响应受到钻具组合、内外钻井液流动以及钻井参数等因素的影响,钻柱动力失稳导致的剧烈振动是井壁坍塌和钻具失效的重要原因.考虑到钻杆和钻铤在刚度和线密度上存在很大的差别,论文将钻柱简化为单阶梯输液管柱,钻井液沿着钻柱内部向下泵入并从环空返回地面.耦合考虑钻柱自重、随时间简谐变化的波动钻压、稳定器以及钻井液的水动力和阻尼力,建立了直井中钻柱横向振动的解析模型.利用有限单元法离散为四阶常微分方程后,采用Bolotin法得到临界频率方程确定系统的不稳定区范围,研究了钻压、钻杆长度、稳定器安装位置、钻井液的流速和密度等参数对系统稳定性影响的机理.研究表明:钻压的平均值和波动幅值都是钻柱失稳的驱动因素,而系统的稳定性对处于受拉状态的钻杆的长度变化不敏感.在论文所研究的参数范围内,降低钻井液流速和密度、下移稳定器的安装位置均有助于增强系统的稳定性.
[Abstract]:The dynamic response of drill string in long and narrow well bore is affected by drilling tool combination, internal and external drilling fluid flow, drilling parameters and other factors. The violent vibration caused by dynamic instability of drill string is the important cause of shaft collapse and drilling tool failure. Considering the great difference in stiffness and linear density between drill pipe and drill collar, the drill string is simplified as a single step infusion string, the drilling fluid is pumped down along the drill string and returned to the ground from the annulus. An analytical model of the lateral vibration of drill string in a vertical well is established by coupling the hydrodynamic force and damping force of the drill string with respect to the weight of the drill string, the fluctuation of drilling pressure with the simple harmonic variation of time, the stabilizer and the drilling fluid. After discretization into fourth order ordinary differential equation by finite element method, the critical frequency equation is obtained by using Bolotin method to determine the range of unstable region of the system. The drilling pressure, drill pipe length and the installation position of stabilizer are studied. The mechanism of the influence of the parameters such as velocity and density of drilling fluid on the stability of the system. The results show that the average value and fluctuation amplitude of drilling pressure are the driving factors of string instability, and the stability of the system is not sensitive to the length change of the drill pipe in the tension state. In the range of parameters studied in this paper, reducing the flow rate and density of drilling fluid and installing the downshift stabilizer will help to enhance the stability of the system.
【作者单位】：西南石油大学机电工程学院;
【基金】：国家自然科学基金(51134004) 石油天然气装备教育部重点实验室(OGE201403-10)资助
【分类号】：TE921.2

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