页岩气井固井套管居中与下入能力研究

在对井筒内管柱受力状态进行科学分析的基础上,建立了长水平段和造斜段套管居中度分析模型,对扶正器的选择和安放间距进行了设计。采用有限元法对FYHFl井及MYHFl井扶正器选择方案和下入方案现场应用效果进行分析,分析结果表明,在井况许可的条件下,水平段应采用API标准扶正器,且每根套管加装1只扶正器,以保证套管的居中度和固井质量;选择合适的扶正器、设置合理的间距能有效减小套管下入阻力,同时明显增强套管串刚度;套管居中度对采用油基钻井液的页岩气水平井固井质量影响明显,套管居中度应该控制在67%以上,并严格控制套管贴边,以免影响水泥环均匀性和压裂效果。

Research on the Running and Centralization of Casing in Shale Gas Well

On the basis of scientific analysis of the force condition of string within well bore,the analysis model for the casing centralization of long horizontal section and buildup section was established.The centralizer selection and installation spacing were designed.Referring to the finite element method,an analysis was conducted to deal with the centralizer selection scheme and installation scheme of the well FYHFl and well MYHFl.The field application effect shows that the API standard centralizer should be adopted in the situation allowed by well conditions and one centralizer should be added to each casing in order to ensure the centralization and cementing quality of casing.Selection of reasonable centralizer and setup of reasonable spacing can effectively decrease running resistance of casing and at the same time increase the rigidity of casing string.The effect of casing centralization on the cementing quality of the shale gas horizontal well which adopts oil-based drilling fluid is remarkable.The casing centralization should be controlled above 67%.The casing welt which affects the evenness of cement sheath should be controlled seriously so as to avoid the influence to the fracturing effect.