一种非均匀地应力下椭圆井眼套管-水泥环-地层力学特性半解析解  

Semi Analytical Solution for Mechanical Properties of Elliptical Borehole Casing-Cement-Stratum System in Non-uniform In-situ Stress Field

作　　者：吴烁 房军[2] 王宴滨 翁炜 贺云超 张德龙 WU Shuo;FANG Jun;WANG Yan-bin;WENG Wei;HE Yun-chao;ZHANG De-long(Beijing Institute of Exploration Engineering, Beijing 100083;College of Petroleum Engineering, China University of Petroleum(Beijing), Beijing 102249, China)

机构地区：[1]北京探矿工程研究所,北京100083 [2]中国石油大学(北京)石油工程学院,北京102249

出　　处：《科学技术与工程》2022年第3期997-1003,共7页Science Technology and Engineering

基　　金：国家科技重大专项(2017ZX05009-003);国家自然科学基金(41802197);中国地质调查局地质调查项目(DD20190137,DD20201102,DD20211338)。

摘　　要：为研究井壁崩落形成椭圆形井眼后套管受力情况,在弹性力学理论的基础上,结合复变函数方法建立了非均匀地应力作用下椭圆形井眼内套管-水泥环-地层组合体应力模型,根据应力边界条件与位移单值条件得到了系统各界面处应力分布的半解析解;并探究了井眼椭圆度、水泥环弹性模量和泊松比对套管外壁径向应力与Mises应力的影响。研究结果表明:与圆形井眼相比,椭圆形井眼能减小套管所受最大应力,降低应力非均匀度;高泊松比、低弹性模量水泥环也有利于减小套管受力。研究成果对井壁崩落段地层钻井液密度、套管规格选取和固井水泥性能设计具有重要的指导意义。During drilling,wellbore collapsing will cause the wellbore to become elliptical.In order to study the stress of casing in elliptical wellbore,a stress model of casing-cement-formation system in elliptical wellbore under inhomogeneous in-situ stress was established on the basis of elastic mechanics theory and complex variable function method.The stress boundary condition and displacement single value condition was used to derive a set of linear equations that could get the stress potential function.On the basis of stress potential function,the analytical solutions of the stress distribution at all directions could be obtained.With that,the effects of hole ellipticity,cement sheath elastic modulus and Poisson's ratio on the radial stress and Mises stress of casing outer wall were discussed.The results show that,compared with circular hole,the elliptical hole can reduce the maximum stress and the stress non-uniformity.The cement sheath with high Poisson's ratio and low elastic modulus can also reduce the casing stress.The results have important gui-ding significance for mud density and casing specification selection,cement performance design in the formation of wellbore caving section.

关 键 词：椭圆井眼 非均匀地应力 套管 应力 半解析解 

分 类 号：TE256[石油与天然气工程—油气井工程]