考虑初始椭圆度的套管抗载能力分析

The Mechanical Properties Analysis of Casing with Initial Ovality

针对套管的不同初始椭圆度建立了套管、水泥环、地层平面应变力学模型。分析认为,在非均匀地应力作用下,套管内壁的径向变形较大,抗载能力明显降低,破坏主要是由地下非均匀地应力引起的;随着初始椭圆度的增加,在地应力作用下套管各部位产生的应力分布不均程度增大,使得套管抗外载能力减弱。建议在生产和使用过程中应严格将套管椭圆度控制在规定的范围内,从而提高套管的抗载能力。

Casing, cement and formation plane strain mechanical model are established, consider-ing casing with initial ovality. Under the non-uniform in-situ stress, displacement of casing inter-nal wall changes greatly, carrying capacity declines obviously, so casing damage is caused by non-uniform in-situ stress. With ovality increasing, equivalent stress increases obviously on the three thickness orientation of casing, so stress distribution is inhomogeneous on casing, and carrying capacity of casing decreases. In order to enhance carrying capacity, initial ovality of casing should be controlled in defined limit.