水平井固井质量对套管变形影响分析

Effect of Cementing Quality on Casing Deformation in Horizontal Wells

针对某井区深井X-1h井中出现的套管变形损坏问题,对比分析了压裂段固井质量与套损位置关系,基于现场数据,建立了套管-水泥环-地层力学耦合模型,分析了套管-水泥环界面胶结失效后形成微间隙的大小、水泥环破坏后的缺失角度以及水泥环缺失方位对套管应力和变形失效的影响。研究结果显示:固井质量不佳对套管的应力及变形失效有显著影响;套管-水泥环界面过大的微间隙会由于套管在内压作用下的鼓胀效应而放大内压的作用;当水泥环缺失角度在45°~60°区间时,套管Mises应力最大,超过套管材料最小屈服强度;当水泥环缺失方位与井周最小主应力方向一致时,套管应力集中最明显,略大于套管材料的最小屈服强度,套管局部发生塑性变形失效。研究结果可为现场固井作业施工提供一定的指导。

Casing deformation occurred in deep well X-1h of a well area.To solve this problem,the relationship between the cementing quality of the fracturing section and the location of casing damage was analyzed.Then,based on field data,a casing,cement sheath and formation mechanics coupling model was built to analyze the effects of the microgap formed by cementation failure of casing and cement sheath interface,the missing angle of cement sheath after being destroyed,and the missing azimuth of cement sheath on the stress and deformation failure of the casing.The research results show that poor cementing quality has a significant impact on the stress and deformation failure of the casing.The excessive microgap at the interface between the casing and the cement sheath amplifies the effect of internal pressure due to the bulging effect of the casing under internal pressure.When the missing angle of the cement sheath is between 45°and 60°,the Mises stress of the casing is the highest,exceeding the minimum yield strength of the casing material.When the missing azimuth of the cement sheath is consistent with the minimum principal stress direction around the wellbore,the stress concentration of the casing is most obvious,slightly exceeding the minimum yield strength of the casing material,and plastic deformation failure occurs locally in the casing.The research results provide some field guidance for cementing operations.