塔河油田固井质量评价影响因素分析

塔河油田主要采用声幅(CBL)及变密度(VDL)测井进行固井质量评价,此种评价方法存在多解性.同时,测井响应还受到固井质量之外的其他因素影响.如仪器刻度、仪器偏心、快速地层、多层套管、薄水泥环等.为减少仪器刻度和偏心对固井质量评价产生的影响,现场施工时,可收集一些同规格但不同井筒环境的自由套管刻度,选择量接近的井筒环境刻度值进行刻度；同时,在入井仪器上加装与套管内径匹配的扶正器,保证仪器在套管中处于居中位置.固井质量评价时,视具体情况,应参考固井、钻井裸眼井测井等有关数据,进行多信息综合评价.条件允许时,可采取SBT(扇区水泥胶结测井仪)等技术进行固井质量评价,该技术适用于大多数尺寸的套管,测量结果不受快地层、仪器偏心、井内流体性质或相对密度的影响、能够更加准确地获得第Ⅰ界面和第Ⅱ界面的胶结信息.

Study on Influential Factors of Well Cementation Evaluation in Tahe Oilfield

The CBL-VDL(Cement Bond Log-Variable Density Log) has been applied to evaluate the well cementation in Tahe oilfield recently.Ambiguity exists when using this method.Log response is influenced by not only cementation quality but also other factors,such as instrument scale,tool eccentricity,high-velocity layer,multi-casing,thin cement mantle and so on.In order to make less influence of the instrument scale and eccentricity on cementation quality,some free pipe scale with the same gauge under various wellbore environment may be collected,and then the scale closest to the wellbore environment is selected for scaling in the field.At the same time,centralizer matched with casing inside diameter should be assembled on the instrument in well,which will ensure the instrument in the middle of the casing.Well cementation evaluation should be comprehensive through many informations on well cementation,drilling,open hole log according to the actual situation.If permitted,SBT technology may be applied for well cementation evaluation suitable to most-size casing.Its measuring results are not influenced by high-velocity layer,tool eccentricity,property or relative density of bore hole fluid,and cementation information at No.Ⅰand Ⅱinterface may be gained more accurately.