Highest-Resolution High-Signal-to-Noise Ratio Sonic Slowness and Application to Brothers Volcano, Kermadec Arc, New Zealand

Abstract

High-resolution and accurate acquisition of underground sonic properties is essential for energy detection and earth exploration. An effective method is proposed to accurately calculate sonic slowness at the highest resolution (receiver spacing of 0.5 ft) with high signal-to-noise ratio (S/N) ratio. The method utilizes super-virtual interferometry to reconstruct a large number of waveforms for slowness extraction using redundant information from overlapping inter-receiver spacing. Synthetic calculations are used to verify the validity of the method, especially in the case of strong noise interference and the presence of damaged channels in the array receivers, to accurately calculate the formation sonic slowness. The theory is applied to process and interpret low data-quality field measurements acquired at Brothers Volcano from the International Ocean Discovery Program (IODP). The processing analysis shows that in the case of very weak formation signals, the residual tool waves from the wireline sonic logging can still interfere with the high-resolution processing, while this method can effectively suppress this interference and accurately obtain the formation sonic velocity.