元坝地区φ146.1mm尾管固井技术难点与对策

Difficulties and Countermeasures for φ146.1 mm Liner Cementing in Yuanba Area

元坝地区已完成11口井的φ146.1 mm尾管固井施工,其中有5口井固井质量不合格,合格率只有54.6%,这严重影响了地层评价及油气勘探开发进程。计算分析认为,不能压稳易导致气窜、窄间隙偏心、环空顶替效率低、井下高温及存在腐蚀性气体是该地区产层固井质量低的主要原因。室内数值模拟结果表明,水泥浆顶替效率随着偏心度的增大近似呈指数降低,而通过改善隔离液的稠度系数与流性指数可有效提高顶替效率,从而提出了合理设计环空液柱结构并采取环空加压措施以确保压稳、改善隔离液的流变性能、应用高温胶乳水泥浆体系等提高固井质量的技术措施,并在元坝11井φ146.1 mm尾管固井中进行了应用,固井质量合格率100%,优良率85.9%。

Eleven wells in Yuanba area were finished with φ146.1 mm liner cementing,among which 5 wells are not qualified,which means only 54.6% are qualified.It retrains the formation evaluation and oil-gas exploration and exploitation.Analysis shows that the main reasons resulting in poor cementing quality are gas kick,low displacing efficiency due to narrow eccentric annulus,high bottom-hole temperature,and existence of corrosive gases,etc.The result of numerical simulation indicates that the displacing efficiency of slurry reduced exponentially with the increase of eccentricity.With the improvement of spacer＇s viscosity coefficient and liquidity index,the displacing efficiency can be improved effectively.A reasonable technical measures was used to improve cementing quality by designing liquid-structure,keeping stable pressure in annular space,improving rheology of spacer,using anti-high temperature latex slurry system,etc.The test in Well Yuanba-11 with φ146.1 mm liner cementing shows that the qualification is 100% and excellent rate is 85.9%.