Laboratory measurement of sonic (1–20 kHz) P‐wave velocity and attenuation during melting of ice‐bearing sand

We measured the acoustic properties of ice-bearing sand packs in the laboratory using an acoustic pulse tube within the frequency range of 1–20 kHz, similar to sonic well-logs. We analyzed how wave velocity and attenuation (the inverse of quality factor) change with ice saturation and measurement frequency during melting. We found strong frequency-dependent correlations for both acoustic parameters with ice saturation. For any frequency within the studied range, velocity decreases and attenuation increases as the ice melts. For lower ice saturations (Si < ∼0.5), attenuation was particularly sensitive to frequency linked to acoustic wave scattering from patchy ice saturation. We used rock physics models with three-phase approaches to assess our experimental results. The comparison highlights the influence of ice formation distribution (i.e., uniform vs. patchy), permeability, and gas content on both velocity and attenuation. Our results pave the way for monitoring ice saturation from sonic measurements, as ice saturation has contrasting effects on velocity and attenuation, and the effects vary with frequency. Overall, this research contributes to a better understanding of the acoustic response of ice-bearing sediments and provides valuable insights for various applications, including permafrost monitoring and natural gas hydrate dissociation studies.