基于虚功原理建立套管外挤力学模型

MODEL OF CASING EXTERNAL EXTRUSION BASED ON THE PRINCIPLE OF VIRTUAL WORK

为了准确地描述侧向载荷作用下套管发生挤毁变形,假设在发生塑性变形时套管的受力变形区形状为对称的两个弧形,基于虚功原理建立侧向载荷作用下的套管损坏力学平衡关系,引入菲涅耳积分推导出套管损坏力学模型.并结合大庆油田工程实际进行了套管挤毁实验,得出新公式的平均相对误差远远小于API公式的平均相对误差,从能量角度出发,为研究在外挤载荷下套管挤毁变形提供新的研究方法,为以后研究相关设计提供参考.

In order to accurately describe casing collapse under lateral load, we assume that the shape of the stress deformation zone of the casing is two arcs in plastic deformation. We establish casing damage mechanics balance relationship based on theprinciple of virtual work under lateral loads, then derive the casing damage mechanics model by the Fresnel integral. With the engineering practice of Daqing oilfield,weconduct casing collapse test. The new formula leads to a far smaller average relative error than that obtained from the API formula. From the viewpoint of energy, the paper provides a new research method for the study of casing collapse deformation under external load.