| Summary: | Broadband (100-4000 Hz) cross-hole seismic data have been acquired at a borehole test site where extensive hydrological investigations have previously been performed, including <em>in situ</em> estimates of permeability. The rock type is homogeneous chalk and fractures and bedding planes have been identified from well logs. High values of seismic attenuation, Q = 22 ≤ 27 ≤ 33, were observed over a 10 m depth interval where fracture permeability values of 20-50 darcy had been recorded. An attempt has been made to separate the attenuation due to scattering and intrinsic mechanisms. The estimated values of intrinsic attenuation, Q = 31 ≤ 43 ≤ 71, have been reproduced using a number of current theories of seismic-wave propagation and fluid-flow-induced seismic attenuation in cracked and fractured media. A model that considers wavelength-scale pressure gradients is the preferred attenuation mechanism. Model parameters were obtained from the hydro-geological and seismic data. However, we conclude that it is not possible to use seismic Q to measure rock permeability remotely, principally because of the inherent uncertainties arising from model parameterisations.
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