Summary

We present a signal processing technique to enhance the resolution of earth formation slowness (or velocity) profiles measured by an array acoustic tool. The enhanced resolution ranges from the conventional resolution of 3.5 ft, the array aperture, to 0.5 ft, the inter-receiver spacing. While use of a shorter subarray is necessary for the resolution enhancement, the decrease in data redundancy and increase in noise contamination pose a problem. The new technique is designated to solve the problem. In this technique, we first window the wave event of interest using the wave’s traveltime information. We then match the wave event at two arbitrary receivers in the subarray by time-shifting one of the receiver’s waveform using a trial slowness value. Finally, the waveform matching is performed for all pairs of receivers allowed by the subarray aperture, so as to maximize the redundancy of information in the wave data. When the waveform mismatch residue is at the minimum for all overlapping subarrays, we obtain the slowness with the resolution of the subarray aperture.

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