An acoustic method to evaluate cement quality in an oil well

The authors present a brief introduction to the construction and principle of the Cement Bond Log Tool. A model of wave propagation and attenuation by the cement in the annulus is then given, and the Bond Percentage Index (BPI) interpretation method is introduced. After some historical errors are analysed, experiments and comparison results for both BPI and the traditional method are described. The limitations of the tool are also discussed. The conclusions are that the analysis, supported by experiments, is correct and that the CBL tool itself should not be blamed for errors but the way it has been interpreted