Pressure‐Dependent Elastic and Transport Properties of Porous and Permeable Rocks: Microstructural Control

Although several studies aimed at linking electrical and hydraulic transport properties in rocks, the existing models remain at most incomplete. Based on this observation, in addition to the transport properties, this contribution investigates the pressure dependence of P wave velocities and porosit...

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Bibliographic Details
Published in:Journal of geophysical research. Solid earth 2017-11, Vol.122 (11), p.8952-8968
Main Authors: Pimienta, Lucas, Sarout, Joel, Esteban, Lionel, David, Christian, Clennell, Michael B.
Format: Article
Language:English
Subjects:
conceptual model
Conductivity
Confining
confining pressure
Earth Sciences
Elastic properties
Electrical resistivity
Evolution
Geophysics
Hydraulic conductivity
Hydraulics
Microcracks
microstructure
Percolation
Permeability
Permeability coefficient
Physical properties
Plateaus
Porosity
porous networks
Pressure
Pressure dependence
Properties
Rock
Rocks
Sciences of the Universe
Seismic velocities
Seismic wave velocities
Transport
transport and elastic properties
Transport properties
Tubes
Velocity
Wave velocity
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Summary:Although several studies aimed at linking electrical and hydraulic transport properties in rocks, the existing models remain at most incomplete. Based on this observation, in addition to the transport properties, this contribution investigates the pressure dependence of P wave velocities and porosity for three porous rocks. Apart from hydraulic conductivity, all physical properties show an important dependence to the confining pressure. In particular, electrical resistivity reaches an asymptote at low confining pressures. Using the measured P wave velocities and effective medium theories, the microcrack density (ρ) and its evolution with confining pressure are estimated. For the three rocks, the microcrack density at which electrical resistivity reaches a plateau is of ρ ~0.13. This value corresponds to the threshold for crack percolation in media containing microcracks exclusively. This suggests that in porous and microcracked rocks, electrical resistivity is controlled by two independent hydraulic pathways of tubes and cracks acting in parallel. In contrast, this percolation threshold is not observed in the permeability data. A simple conceptual model is finally introduced that explains the fundamental differences between transport properties. Key Points Measured pressure dependent of P wave velocity and electrical resistivity, and pressure independent permeability, for three porous rocks Microstructural insight from pressure dependence of electrical resistivity and P wave velocity Microstructural insights from comparing with pressure independent permeability: role of the network types on the links between transport properties
ISSN:2169-9313
2169-9356
DOI:10.1002/2017JB014464