水泥环缺陷对套管接头螺纹牙承载能力影响分析

发布时间：2018-05-12 13:16

本文选题：套管螺纹牙 + 水泥环缺陷　；参考：《西南石油大学》2017年硕士论文

【摘要】：套管接头附近的水泥环缺陷会直接影响到螺纹牙的受力情况,并且往往会导致螺纹牙出现应力集中现象,甚至引起套管损坏。目前国内外针对套管接头附近的水泥环缺陷对螺纹牙的承载能力影响研究还比较少,而且建立的"地层-水泥环-套管"平面耦合系统模型,考虑的因素不够全面。本文基于弹性力学,首先将问题简化为平面应变系统,建立套管在水泥环完好,且受到均匀地应力作用时的等效应力计算模型;接着,考虑套管内外螺纹牙的变形协调因素,建立三维套管在水泥环完好,且受到均匀地应力作用时螺纹牙的应力分布计算模型;在此基础上,推广水泥环含缺陷时三维螺纹牙应力分布计算方法;然后根据现场资料数据,建立不同参数的水泥环缺陷模型;在忽略轴向载荷的情况下,利用有限元软件对不同缺陷下的模型进行仿真模拟,得到相应的螺纹牙应力分布规律;然后探讨不同类型的载荷与缺陷共同作用对套管的承载能力影响;最后单独研究轴向载荷的影响情况,给出复杂工况下含水泥环缺陷的套管螺纹牙最大等效应力计算方法以及不同轴向载荷的影响程度系数。并得出以下主要结论:(1)论文第二章提出的理论方法适用于计算低轴向拉力的浅井或无轴向拉力的水平井段套管螺纹牙应力,含高轴向拉力时需采用修正后的公式计算。(2)螺纹牙的变形协调因子不会随载荷大小而改变,只会随模型几何参数以及载荷的类型而发生改变。(3)轴向拉力不会改变缺陷对套管螺纹牙承载能力的影响规律,只会按一定比例增强缺陷的影响力。(4)处于第一界面的缺陷对套管螺纹牙的最大等效应力影响总是不同程度的较第二界面的缺陷大;套管偏心会加剧缺陷的影响效果。
[Abstract]:The cement ring defect near the sleeve joint will directly affect the stress of the thread tooth and will often lead to the stress concentration phenomenon of the thread tooth and even the casing damage. At present, there is little research on the influence of cement ring defect near casing joints on the bearing capacity of thread teeth, and the factors considered in the plane coupling system model of "stratum cement sheath and casing" are not comprehensive enough. In this paper, based on elasticity, the problem is simplified as a plane strain system, and the equivalent stress calculation model of casing is established when the cement sheath is intact and subjected to uniform in-situ stress. The stress distribution calculation model of the thread teeth is established when the cement casing is intact and subjected to uniform in-situ stress. On this basis, the calculation method of the stress distribution of the 3D thread teeth with defects in the cement sheath is extended, and then, according to the field data, the calculation method of the stress distribution of the three dimensional thread teeth is extended. The defect model of cement ring with different parameters is established, and the stress distribution law of thread tooth is obtained by using finite element software to simulate the model under different defects, while ignoring the axial load. Then the influence of different types of load and defect on the bearing capacity of casing is discussed. Finally, the influence of axial load on casing load is studied separately. The calculation method of maximum equivalent stress of casing thread teeth with cement ring defects under complex working conditions and the influence coefficient of different axial loads are given. The main conclusions are as follows: (1) the theoretical method proposed in Chapter 2 of the paper is applicable to the calculation of casing thread stress in shallow wells with low axial tension or in horizontal wells without axial tension. In the case of high axial tension, the modified formula is used to calculate the deformation coordination factor of the thread teeth, which will not change with the size of the load. The axial tension will only change with the geometric parameters of the model and the type of load.) the axial tension will not change the influence of defects on the bearing capacity of the casing thread. The effect of the defect at the first interface on the maximum equivalent stress of the casing thread is always greater than that of the second interface, and the influence of the casing eccentricity will aggravate the effect of the defect.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE931.2

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