腐蚀缺陷套管的剩余强度研究  

Study on residual strength of corrosion defect casing

作　　者：张智[1] 孔维伟[1] 刘志伟[1] 王汉[1] 张庆生[2] 张诚[2] 安思彤[2] 

机构地区：[1]西南石油大学油气藏地质及开发工程国家重点实验室,成都610500 [2]中国石油化工股份有限公司中原油田分公司石油工程技术研究院,河南濮阳457001

出　　处：《中国科技论文》2016年第21期2467-2472,共6页China Sciencepaper

基　　金：国家科技重大专项资助项目(2016ZX05017-003);四川省科技厅(青年基金)资助项目(2016JQ0010);四川省省属高校科技创新团队建设计划资助项目(13TD0026)

摘　　要：针对酸性气井中套管的腐蚀缺陷形貌差异较大的问题,考虑到套管强度计算模型不能完全涵盖各种腐蚀形貌条件下的强度计算,同时受到实验室强度测试的局限性,采用有限元方法建立了不同腐蚀形貌特征下的套管强度计算模型,并引用文献数据验证了该模型的合理性和可行性。结合四川某酸性气井对套管性能进行实例分析,从均匀腐蚀和点蚀等角度出发,分析了温度、内压对套管等效应力的影响,研究了套管剩余强度随腐蚀深度增加的变化规律,以及点蚀开口直径大小对套管剩余强度的影响。结果表明,温度的升高,腐蚀套管的等效应力呈现持续上升趋势;随着内压的增加,腐蚀套管的等效应力先降低,再逐渐增大。同时腐蚀深度对套管强度的影响显著,随着腐蚀深度的增加,点蚀和均匀腐蚀套管的剩余强度均持续降低。另外,对于相同深度的浅半球形腐蚀坑,点蚀开口直径越大,套管的剩余强度越大。该结果可为酸性气井套管柱安全评价提供依据。Aiming at the problem of the relatively significant difference of casing corrosion defects in acid gas wells, taking into ac- count the incompleteness of casing strength calculation model about various corrosion morphologies and the limitation of laborato- ry strength tests, the research established a casing strength calculation model under different corrosion morphologies by the finite element method （FEM）. The rationality and feasibility of the model has been verified by the literature data. In combination with an acid gas wells in Sichuan, the performance of casing was analyzed by quoting reference data. From the point of uniform corro- sion and pitting corrosion, the effect of temperature and internal pressure on casing equivalent stress was analyzed, the variation law of casing residual strength with corrosion depth was studied, and the effect of the size of the pitting opening diameter on the casing residual strength was also analyzed. The results show that the equivalent stress of the corrosion casing increases with the increase of temperature. The equivalent stress of the corrosion casing decreases and then increases gradually with the increase of internal pressure. The influence of corrosion depth on casing strength is significant. With the increase of corrosion depth, the re sidual strength of corrosion and uniform corrosion casing decreases continuously. In addition, for the shallow hemisphere pitting, the larger the pitting opening diameter is, the greater the casing strength is. The results can provide the basis for the safety eval- uation of casing string in acid gas wells.

关 键 词：套管 腐蚀缺陷 酸性气井 剩余强度 有限元分析 

分 类 号：TE931.2[石油与天然气工程—石油机械设备]