中文摘要：

四川地区部分页岩气井在采用大排量分段压裂工艺施工过程中出现套管变形的现象,严重影响了页岩气井的正常生产。为此,运用ABAQUS软件建立了温压耦合下的套管-水泥环-地层受力有限元模型,模拟压裂过程中套管应力以及组合体温度场分布特征,分析了不同注液温度下,套管偏心及水泥环缺失对套管应力的影响规律。研究结果表明：大排量压裂施工中,套管应力随着偏心距的增加而减小,温降对套管应力的影响较大;不同注液温度下,套管应力随水泥环周向缺失的变化规律基本一致,温降对套管应力的影响呈先降后增趋势;水泥环径向缺失位置以及深度的变化对套管应力的影响较小,温度变化是主控因素;套管偏心下,水泥环缺失以及温降的共同作用均会增加套管应力。研究成果可为页岩气开发提供理论指导。

英文摘要：

Some shale gas wells in Sichuan have experienced casing deformation under large displacement multistage fracturing operation,which has seriously influenced the shale gas wells regular production. To address the issue,a casing-cement sheath-formation stress finite element analysis model under heat-mechanical coupling condition has been established with ABAQUS software to simulate stress distribution of casing and temperature distribution of the system during fracturing. With this model,under different injection fluids temperatures,the effects of casing eccentricity and cement sheath defectiveness on the casing stress has been analyzed. The results show that,in the fracturing process with high displacement,the eccentricity of casing will result in a decline of the casing stress,and the temperature decline have a great influence on casing stress. The casing stress increases with the increase of the cement sheath circumferential discontinuity under different injection fluid temperature. The influence of fluid temperature on the casing stress showed a trend of increase after down first. The influence of the missing location and the depth of the cement sheath on the casing stress are small. The injection fluid temperature is the main casing stress control factor. With the eccentricity of the casing,the combined effects of the temperature decline and the missing of cement sheath would result in greatly increased casing stress. The study method and results could provide theoretical supports for shale gas development in the future.