A Multiple Filtering and Correlation Technique for Cased Hole Acoustic Data Processing
F. Kong, X. Tang, Y. Su and C. Jiang
Event name: 81st EAGE Conference and Exhibition 2019
Session: WL & LWD Processing and Interpretation
Publication date: 03 June 2019
Info: Extended abstract, PDF ( 558Kb )
Price: € 20
In cased-hole acoustic logging, estimating the formation velocity is often problematic when casing is poorly bonded with formation. The overwhelmingly large casing waves dominate the measured waveforms and overlap with the low coherence, weak formation arrival, contributing to the failure of conventional semblance processing method. To tackle this problem, we present a filter frequency semblance array waveform signal processing technique. The multiple filter technique is first used to filter the measured waveforms. We then apply the n-th root stacking method to the filtered signals. Consequently, the coherence of formation signal on the obtained three-dimensional semblance correlogram is significantly enhanced and clearly separated with the casing waves. The advantage of the new method is demonstrated using a field data example.