抗高交变载荷水泥浆的研制及其在涪陵页岩气井的应用

Development of an Anti-Deformation Cement Slurry under Alternative Loading and Its Application in Fuling Shale Gas Wells

针对页岩气井普遍存在的套管环空带压问题,从提高固井水泥环长久密封完整性角度出发,研制了具有钢筋混凝土力学性能的絮状弹韧性材料DeForm,并以其为基础配制了一种适应页岩气井大型分段压裂的抗高交变载荷水泥浆。室内性能评价试验结果表明,该水泥浆具有优良的弹韧性和耐久性,可有效提高水泥环的抗交变载荷能力,实现水泥环与套管的同步形变,保证井筒的长久密封完整性。该水泥浆在涪陵页岩气田9口井进行了现场应用,固井优质率达到88.9%,套管环空带压率为0,效果非常显著,为预防页岩气井套管环空带压提供了新的技术途径。

To sustain casing pressure in shale gas wells,a flocculent elastic material DeForm with the function like rebar in concrete was developed with the goal of improving the long-term sealing integrity of the cement sheath.Using DeForm as the basis of its chemical composition,an anti-deformation cement slurry under alternative loading suitable for large scale staged fracturing in shale gas well was prepared.The indoor performance evaluation results demonstrated that the system has excellent elastic toughness and durability,which can effectively improve the ability of cement sheath to resist alternative loading,to bring about synchronous deformation of casing and cement sheath and to ensure the long-term sealing integrity of wellbore.This cement slurry system has been successfully applied in 9 wells in the Fuling Shale Gas Field,with excellent cement job rating 88.9%and no sustained pressure in casing annulus.With such remarkable application results,the cement slurry will provide a new way in preventing sustained casing pressure in shale gas wells.