深层气井水泥环局部缺失对套管外载影响规律分析  

Influence of Local Missing Cement Sheath on the External Load of Casing in Deep Gas Wells

作　　者：李猛 陈怡朴 程文平 闫炎 吴梦霞 王强 LI Meng;CHEN Yipu;CHENG Wenping;YAN Yan;WU Mengxia;WANG Qiang(School of Petroleum and Natural Gas Engineering,Chongqing University of Science and Technology,Chongqing 401331,China;China Petroleum Technology and Development Corporation,Beijing 100028,China;State Key Laboratory of Oil and Gas Equipment,CNPC Tubular Goods Research Institute,Xi'an,Shaanxi 710077,China)

机构地区：[1]重庆科技大学石油与天然气工程学院,重庆401331 [2]中国石油技术开发有限公司,北京100028 [3]中国石油集团工程材料研究院有限公司,油气钻采输送装备全国重点实验室,陕西西安710077

出　　处：《石油管材与仪器》2024年第3期11-18,I0004,共9页Petroleum Tubular Goods & Instruments

基　　金：国家自然科学基金面上项目“耦合动力土反力作用的深水井口多轴疲劳理论和时变可靠度研究”(编号:51974052);中国博士后科学基金资助项目“地层滑移条件下空心水泥对套管变形的缓解机理与套变程度可控性研究”(编号:2023M743886);页岩气评价与开采四川省重点实验室资助项目“页岩油气水平井压裂过程中套损机理与防治措施研究”(编号:YSK2023004)。

摘　　要：深层气井长封固段固井质量不佳易引发水泥环局部缺失,导致套管使用寿命下降。对此,通过建立有限元模型分析了水泥环力学参数、缺失角度、缺失厚度及套管内压力对套管力学完整性的影响。结果显示,当前工程参数条件下,水泥环缺失后套管等效应力最大值出现在套管内壁,套管最大等效应力随水泥环弹性模量的增大而减小;当水泥环弹性模量小于一定值时,水泥环缺失处套管内壁最大等效应力超过套管设计安全应力;套管应力随泊松比的变化规律与弹性模量的变化规律相反,但相对影响较小。随水泥环缺失角度的增加,套管内外壁应力先增加后减小,在水泥环缺失角度为45°时,套管内壁应力最大,超过45°套管应力有所降低,但易造成后期“偏心”。套管应力最大值随着缺失厚度的增加而增加。随着井筒内压力的增加,水泥环缺失处套管内外壁应力均为先减小后增加,且内压力超过一定数值后,套管最大等效应力由内壁转移至外壁。所得结论可为深层气井长封固段固井提供有益参考。Poor cementing quality in the long cementing section of deep gas wells can easily lead to local missing of cement sheath,resulting in a decrease in the service life of the casing.This article analyzes the effects of mechanical parameters,missing angle,missing thickness,and internal pressure of the cement sheath on the mechanical integrity of the casing by establishing a finite element model.The results show that under the current engineering parameter conditions,the maximum equivalent stress of the casing occurs on the inner wall of the casing after the cement sheath is missing,and the maximum equivalent stress of the casing decreases with the increase of the elastic modulus of the cement sheath.When the elastic modulus of the cement sheath is less than a certain value,the maximum equivalent stress on the inner wall of the casing where the cement sheath is missing exceeds the design safety stress of the casing.The variation law of casing stress with Poisson′s ratio is opposite to that of elastic modulus,but the influence is relatively small.As the angle of missing cement sheath increases,the stress on the inner and outer walls of the casing first increases and then decreases.When the angle of missing cement sheath is 45°,the stress on the inner wall of the casing is the highest.If the angle exceeds 45°,the stress on the casing decreases slightly,but it is easy to cause later eccentricity.The maximum stress of the casing increases with the increase of the missing thickness.As the pressure inside the wellbore increases,the stress on the inner and outer walls of the casing at the missing cement sheath decreases first and then increases.After the internal pressure exceeds a certain value,the maximum equivalent stress on the casing shifts from the inner wall to the outer wall.The conclusions obtained can provide useful references for the long cementing section of deep gas wells.

关 键 词：水泥环缺失 套管应力 缺失角度 缺失厚度 有限元 

分 类 号：TG444[金属学及工艺—焊接] TG445