A novel approach to identify the ultrasonic echoes in inspecting well cementing quality

This paper presents an approach based on the Continuous Wavelet Transform (CWT) and the Fourier transform (FT) to identny the ultrasonic echoes in inspecting oil well cementing quality.First,CWT is used to process echo signals.Then the spectra of the results in some specific scale-time segments are calculated as pattern features.The research results show that the theoretical calculations basically agree with experimental results..Compared with the approach based only on the spectra or Discrete Wavelet transform,our approach has the adVantages of fine analyzing scales,stable features and high recognition rate.It is very suitable to identify the echo signals whose spectra vary with time.