Potential of seismic attenuation for geotechnical investigation of carbonate subsurface

Seismic wave attenuation has a great potential for studying saturated and fractured media, due to its high sensitivity to the geotechnical properties of geological media. However, accurately estimating this parameter can be challenging due to its sensitivity to signal noise, particularly in heterogeneous media such as carbonate rocks. This explains the few number of attenuation studies carried out in carbonate rocks compared to sandstones, and the ambiguity around its mechanisms and its relationship with geotechnical properties. To investigate further, we conducted an experimental study of ultrasonic waveform signals (0.5¬-3 MHz) reordered under dry and fully saturation conditions in thirteen samples covering a wide range of geotechnical properties, and subjected them to effective pressure. The resulting increase in attenuation magnitudes and their variation with pressure due to brine saturation were more pronounced than in velocity magnitudes, confirming the higher sensitivity of attenuation to fluid content. However, understanding the relationship between attenuation and geotechnical properties required a careful examination of the results and more elucidation about attenuation mechanisms. We suggested that multiple attenuation mechanisms coexist, including scattering, cracks slipping, solid frictional relative motion, and global and squirt flow.