[SCG57-01] Combined X-ray microtomography and elastic wave velocity measurements of porous material at in situ high pressures
Keywords:X-ray microtomography, elastic wave velocity, high pressure
In this study, we introduce a new approach, which combines in situ high pressure experimental observations on elastic wave velocity and X-ray microtomography measurements with lattice-Boltzmann analysis to understand the connection between elastic wave velocity and structural properties such as porosity and permeability. Combined X-ray microtomography and elastic wave velocity measurements were carried out in a 250-ton press with a rotation anvil apparatus at beamline 13-BM-D (GSECARS) of the Advanced Photon Source, USA. Experiment was conducted on a simple analog material, porous aluminum, in a Paris-Edinburgh-type high-pressure cell at pressure conditions between 0.14 and 1.36 GPa. Porosity was observed to have a strong inverse dependence on pressure up to ∼0.9 GPa, while permeability has an anisotropic dependence on pressure. Elastic wave velocity and Poisson’s ratio all increase with pressure, with P-wave velocity agreeing well with the Hashin–Shtrikman upper bound under high porosity conditions. These results demonstrate a new methodology combining experimental tools of X-ray microtomography and elastic wave velocity measurements and analytical method to provide cross-property links between microscopic structure and macroscopic elastic wave velocities. Future investigations on more complex rock samples may have important implications for our understanding of the nature of subduction zones.