Possibility of Fluid Flow Characterization via a Geophysical Signal: Experimental Study on the Krauklis Wave Under Fluid Flow

Abstract Krauklis waves are generated by pressure disturbances in fluid‐filled cavities and travel along the solid‐fluid interface. Their far‐field radiation, observed in seismic data from volcanoes or hydraulic fracturing, is known as long‐period events. Characterized by low velocity and resonance, Krauklis waves help estimate fracture size and discern fluids in saturated fractures. Despite numerous theoretical models analyzing Krauklis waves, the existing paradigms are founded on static flow conditions. However, in geological contexts, the assumption of static flow may not be valid. We developed an experimental apparatus using a tri‐layer model consisting of a pair of aluminum plates to examine the effect of fluid flow on Krauklis waves. We employed an infusion syringe pump to inject fluids into the fracture under different flow rates. We used water, oil, and an aqueous solution of Polyethylene glycol as fracture fluids. We calculated resonant frequency, phase velocity, and quality factor to characterize the Krauklis waves. Our findings reveal that an increase in flow rate leads to a higher phase velocity, higher quality factor, and a shift to higher resonant frequency when the flow is in the direction of initial wave propagation while decreasing amplitude. Additionally, when the flow is in the opposite direction of initial wave propagation, we note higher wave absorption and distortion of the Krauklis waves. Our observations unequivocally affirm that fluid flow leaves strong signatures on the Krauklis waves, providing a robust basis for characterizing fluid dynamics within geological settings through the analysis of Krauklis wave.