套管-地层系统套管载荷的弹塑性理论分析  

Study on casing load in a casing-stratum system by elastoplastic theory

作　　者：陈朝伟 蔡永恩[2] 

机构地区：[1]中国石油集团钻井工程技术研究院 [2]北京大学地球物理系

出　　处：《石油勘探与开发》2009年第2期242-246,共5页Petroleum Exploration and Development

基　　金：国家自然科学基金(40521002)

摘　　要：对套管-地层系统在均匀地应力条件下的套管载荷进行弹塑性理论分析。采用Mohr-Coulomb准则,给出了受内外压厚壁筒弹、塑性区的位移和应力分布的解析解,由该解析解可直接退化得到Tresca准则条件下厚壁筒的位移和应力分布。将套管-地层系统看作是岩石和钢材两种不同材料厚壁筒的组合,在解析解的基础上,分别推导出套管-地层系统仅地层进入塑性和仅套管进入塑性两种情况下的套管载荷和极限地应力解析表达式。实例分析表明,仅地层进入塑性时,套管载荷比弹性解大,最大增幅3%;仅套管进入塑性时,套管载荷比弹性解小,减小幅度达到6%。上述结果可应用于套管设计和均匀地应力条件下的套管载荷计算。Casing load is studied with the elastoplastic theory in a casing-stratum system under uniform in-situ stress. The solutions of displacements and stresses of the elastic and plastic region for a thick-walled cylinder are deduced with the Mohr-Coulomb criterion, from which the solutions for the Tresca criterion can be deduced directly. On the basis of the solutions, the casing load and the limit in-situ stress are studied in a casing-stratum system when stratum or casing is in plasticity separately. Analysis shows that when stratum is in plasticity, casing load is lager than that of elastic solution （3%）, while, when casing is in plasticity, casing load is less than that of elastic solution （6%）. The results can be applied in casing design and casing load calculating under uniform in-situ stress.

关 键 词：套管-地层系统 弹塑性 解析解 套管载荷 

分 类 号：TE256[石油与天然气工程—油气井工程]