Enhanced waveform analysis for target modes of borehole waves

A system comprising:

• an acoustic logging tool having a receiver array of two or more receivers, the acoustic logging tool configured to acquire noisy data including a plurality of measured waveforms;
• at least one processor in communication with the acoustic logging tool, wherein the processor is coupled with a non-transitory computer-readable storage medium having stored therein instructions which, when executed by the at least one processor, cause the at least one processor to:
• divide the plurality of measured waveforms into two or more common-gathers of gathered waveforms;
• calculate a travel time curve for a selected target mode of each of the two or more common gathers;
• align waveforms of the selected target mode based on the travel time curve to generate aligned waveforms with zero apparent slowness;
• generate a coherence-based frequency-wavenumber (F-K) filter by calculating a coherence map between waveforms at different depth indices;
• adaptively filter the aligned waveforms to suppress non-target mode waves and generate filtered waveforms, wherein adaptively filtering the aligned waveforms includes applying the coherence-based F-K filter;
• generate enhanced target mode waveforms based on the filtered waveforms and the travel time curve, the enhanced target mode waveforms divisible into two or more common-gathers of enhanced target mode waveforms;
• and
• generate an enhanced dispersion curve of the selected target mode from the two or more enhanced common-gathers, wherein the enhanced dispersion curve includes enhanced signal-to-noise ratios for the selected target mode of the gathered waveforms and suppression of non-target modes relative to the noisy data.

An apparatus comprising:

• an acoustic logging tool having a receiver array of two or more receivers, the acoustic logging tool configured to acquire noisy data including a plurality of measured waveforms;
• at least one processor in communication with the acoustic logging tool, wherein the processor is coupled with a non-transitory computer-readable storage medium having stored therein instructions which, when executed by the at least one processor, cause the at least one processor to:
• divide the plurality of measured waveforms into two or more common-gathers of gathered waveforms;
• calculate a travel time curve for a selected target mode of each of the two or more common gathers;
• align waveforms of the selected target mode based on the travel time curve to generate aligned waveforms with zero apparent slowness;
• generate a coherence-based frequency-wavenumber (F-K) filter by calculating a coherence map between waveforms at different depth indices;
• adaptively filter the aligned waveforms to suppress non-target mode waves and generate filtered waveforms, wherein adaptively filtering the aligned waveforms includes applying the coherence-based F-K filter;
• and
• generate enhanced target mode waveforms based on the filtered waveforms and the travel time curve, the enhanced target mode waveforms divisible into two or more common-gathers of enhanced target mode waveforms, wherein the enhanced dispersion curve includes enhanced signal-to-noise ratios for the selected target mode of the gathered waveforms and suppression of non-target modes relative to the noisy data.