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Micro X-ray CT Imaging of Pore-Scale Changes in Unconsolidated Sediment under Confining Pressure
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 80th EAGE Conference and Exhibition 2018, Jun 2018, Volume 2018, p.1 - 5
Abstract
Summary
Micro X-ray computed tomography was used to image confining-pressure induced changes in a dry, unconsolidated quartz sand pack while simultaneously recording ultrasonic P-wave velocities. We visually observed a reduction in porosity by more than a third as well as extensive grain damage, changes in grain size distribution and an increase in coordination number and contact radius with increasing confining pressure. We used porosity, contact number and contact radius to compute P-wave velocities with the Hertz-Mindlin contact-radius model. Our observations showed that numerous assumptions of the widely used Hertz-Mindlin model are violated in angular sediments and the model drastically overpredicts velocities.
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