石油套管残余应力对抗压溃强度影响的数值模拟

Study of Effect of Residual Stress on Compressive Strength of Casing Pipe by FEM

运用弹性力学理论,建立石油套管的力学模型,通过有限元计算,得到残余应力与石油套管抗压溃强度之间的关系。研究表明残余应力在很大程度上影响着石油套管的抗压溃强度,当切向残余应力存在时,拉应力明显有利于提高石油套管的抗压溃强度,而压应力的存在会显著降低石油套管的抗压溃强度;而当在石油套管上存在轴向残余应力时,拉应力使石油套管的抗压溃强度降低,而压应力使石油套管的抗压溃强度有所提高;非均匀分布挤压载荷对石油套管抗压溃强度的影响同均匀分布载荷相似。因此,为了提高石油套管的抗压溃强度,应根据管体的受力状态,使石油套管的管体上产生最佳的残余应力值,提高石油套管的抗压溃强度,延长使用寿命。

Based upon the elasticity theory, a mechanical model for the casing pipe was built and the relationship between residual stress and compression strength was developed by FEM. The results show that the residual stress in casing pipe mainly influences on the compressive strength. When the tangential residual stress exists, the stretching stress can enhance and the crushing stress can remarkably reduce the compressive strength. When the axial residual stress exists, the stretching stress can reduce and the crushing stress can enhance the compressive strength. The non-uniform extrusion stress imposes the same effect as the uniform extrusion stress. Thus, to enhance the compressive strength and the life span of the casing pipe, the residual stress should be controlled according to the situation of the stress.