Stratum Identification of Drilling Based on Complex Morlet Wavelet

According to the bit excited in the layers with different characteristics of the vibration signal,the delay information of the bit into an another stratum can not be extracted accurately by real Short Time Fourier Transform(STFT) and wavelet transform in the case of low SNR.This paper puts forward a complex Morlet wavelet transform analysis.The message of the amplitude and the phase has a good sensitivity to the mutation,so the mutation position can be extracted and then the time when the drilling bit is into different stratum is determined in real time.Experimental result prove that complex Morlet wavelet transform can accurately characterize the time-frequency information and the delay time information.Compared with the STFT and the real wavelet transform,complex Morlet wavelet transform has a better time localization and noise suppression capabilities.