Wavelet transform of geophysical well logging signal and its application to sequence division

The purpose of this study was to identify the sequence interfaces from geophysical well log data using the wavelet transform. Logging signal representing lithology and physical properties embrace much information related to sedimentary cycles. By the wavelet transform, the logging signals are expended from one-dimension depth domain to two-dimension depth-scale domain, making stratum cycling structure much clearer. In the process, time-frequency characteristics of logging signal are obtained from the wavelet coefficients chromatogram, which can be used to detect periodic components of logging signal on different scales. Based on the wavelet coefficients chromatogram and oscillation characteristics of wavelet coefficients line, different sequence boundaries can be identified easily. This method is an effective complement for traditional logging sequence stratigraphy by providing a new idea and an efficient approach for the quantitative division of sequence.