Abstract:

Fractured reservoir become more and more important role in reservoir exploration, and how to identify and evaluate this kind of reservoir is one of the focuses point in logging evaluation. Because of the Cohen time-frequency analysis method behave the advantages to analysis signals both in time and frequency domain, and the Hilbert-Huang transform (HHT) can be decomposed any signals into a finite number of intrinsic mode functions (IMF) ,since the IMF has the single component characteristics, this characteristics satisfied the need for Cohen time-frequency analysis method. The authors make use of these two advantages to extract the useful properties of array acoustic logging signals, the new method is used in extracting the fractured properties embedded in the array acoustic signals, the tested results had showed this method can effective extracting the time-frequency distribution characteristics of fractured formation. And this joint time frequency analysis method can further be used to extract more and more information embedded in the array acoustic logging signals to evaluate the reservoir properties.

Key words: fractured formation, acoustic logging, Cohen time-frequency analysis, Hilbert-Huang transform, empirical mode decomposition, joint time frequency characteristics