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Fluid Injection Under Differential Confinement

Accepted version
Peer-reviewed

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Article

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Abstract

Laboratory studies of cavity initiation and propagation in weak or cohesionless materials rely on post-test observations to assess fracture geometry. The experimental setup in this work is a Hele-Shaw cell, which allows for visualization of cavity initiation and propagation within the sand pack, modified to apply differential confinement to a fully 3D specimen. Injection experiments with glycerine at different concentrations and at varying injection rates were conducted with anisotropic boundary conditions on loose sand. The fracture initiation and evolution was observed under various flow rates and viscosities. Infiltration and dislocation of particles were the main mechanisms observed in the tests. Fracture-like channels initially developed in a circular shape due to cavity expansion but then formed rod shapes (shear bands, material fluidization) where an anisotropic stress was applied. This transition from circular to elongated cavity appeared earlier in the tests with higher viscosity fluids, while higher injection rates produced wider openings as the larger volume of fluid was able to displace more particles. Although the cavity showed directionality in all cases, it became less confined to the propagating plane as the flow rate increased. For higher viscosities, the cavities tended to be more circular whilst for lower viscosities the cavities showed more directionality.

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Keywords

Flow in porous media, Three-dimensional injection experiments, Poorly consolidated formations, Loose sand

Journal Title

Transport in Porous Media

Conference Name

Journal ISSN

0169-3913
1573-1634

Volume Title

139

Publisher

Springer Science and Business Media LLC

Rights

All rights reserved
Sponsorship
Engineering and Physical Sciences Research Council (EP/P013848/1)