Abstract

Micro X-ray computed tomography was used to image confining-pressure induced changes in a dry, unconsolidated quartz sand pack while simultaneously recording ultrasonic Pwave velocities. The experiments were performed under insitu pressure of up to 4000 psi. We visually observed a reduction in porosity by more than a third of the initial value as well as extensive grain damage, changes in pore and grain size distribution and an increase in contact number and contact radius with increasing confining pressure. We further used porosity, contact number and contact radius to model P-wave velocity with the contact-radius model by Bachrach et al. (1998)