大斜度井修井作业卡点预测数值模拟方法

Numerical Simulation Method for Predicting the Sticking Point in Highly Deviated Well Workover

现在的卡点计算公式大多采用提升法,应用微积分理论计算卡点,只适应于直井,且单一管柱卡点计算公式只适合L形斜井模型,遇到不同井眼轨迹的定向井或水平井其合理性和准确性就无法验证。为此,基于有限元理论,提出大斜度井修井管柱力学数值模拟分析方法,对简化实例模拟仿真,并与理论模型的计算结果进行对比分析。分析结果表明,数值模拟仿真法能真实、准确地计算卡点位置;管柱在井眼中受屈曲失稳和摩擦的影响,上提力与管柱变形量之间将不再是完全的线性关系,可通过数值模拟的方法得到上提力的下限范围。

At present the calculation formula for sticking point often adopts the lifting scheme, applying differential and integral calculus theory to calculate sticking point. This can apply only to the diameter. Moreover, the calculation formula for the sticking point of single string is only suitable for L-shaped deviated well model. Its rationality and accuracy cannot be verified with respect to the directional well or horizontal well with different hole trajectories. Therefore, on the basis of finite element theory, the mechanical numerical simulation analysis method for the workover string of highly deviated wells was proposed. The example simulation was simplified and it was compared with the calculation result of the theoretical model. The analysis shows that the numerical simulation method can conduct a real and precise calculation of the sticking point position. The relation of the pulling force to the string deformation amount will no longer be a completely linear one due to the effects of buckling instability and friction on string in borehole. The lower limit scope of pulling force can be obtained by the numerical simulation method.