摘要
利用弹性杆的大变形理论,在拖带坐标系下建立了斜直井孔约束下钻柱的平衡微分方程。为了比较端部不同约束对钻柱屈曲行为的影响,分别采用两端铰链支承和一端滑动固定、一端铰链支承模型对钻柱的控制微分方程进行了级数求解,并用迦辽金方法在空间域内加权消残,得到了屈曲发生时无量纲的结构参数与井孔几何参数之间的关系,并绘制了相应的分岔值曲线。研究结果表明,随着井斜角的增加和井孔视半径的减小,钻柱发生屈曲的临界载荷亦越来越大。得到的分岔值曲线对于预测钻柱屈曲行为的产生具有一定的参考意义。由于两个模型给出几乎相同的分岔值,说明控制斜直井孔内钻柱屈曲行为的主要因素是井壁的侧向约束,而端部不同边界条件的影响可以不计。
Based on the theory of large spatial deflection of elastic rod, this paper sets up a differential equilibrium equation governing tubulars constrained in inclined wellbores in convected coordinate system. To compare the effects of end constraints of tubulars on its buckling behavior, two different models （a pin-pinned model and a pin-fixed model） of tubulars are employed. The differential equation is solved with series method. The residuals in space domain are eliminated by Galerkin method. The relationships between the dimensionless parameters of tubular structures and the wellbore geometry are presented graphically. The results show that the higher the wellbore inclination angle and the smaller the radial clearance, the larger the critical weight-on-bit to initiate tubular buckling. The bifurcation value curves have reference significance to some extent in predicting the buckling behavior of tabulars. As two different models give almost the same bifurcation values, it seems that the controlling factor in the buckling behavior of tubulars in inclined wellbores is the lateral constraint of the well wall, whereas the effect of different end conditions can be neglected.
出处
《工程力学》
EI
CSCD
北大核心
2007年第1期167-172,共6页
Engineering Mechanics
关键词
钻柱
临界钻压
斜直井孔
正弦屈曲
井斜角
tubular
critical weight-on-bit
inclined wellbores
sinusoidal buckling
wellbore inclination angle
