Compaction localization in geomaterials

Event details
Date | 07.10.2016 |
Hour | 12:15 › 13:15 |
Speaker | Prof. Dr Patrick Baud, Laboratoire de Geophysique expérimentale, Ecole et Observatoire des Sciences de la Terre (EOST), Strasbourg, France |
Location | |
Category | Conferences - Seminars |
The development of deformation bands has primary importance on fluid flow in subsurface geologic reservoirs and aquifers. Among diversity of compactant failure modes in porous rock, compaction bands are a type of deformation band characterized by a reduction in porosity and permeability across the thin band structure. Mechanical data and microstructural observations on sandstone demonstrate that compaction bands can develop in compositionally heterogeneous rock and are the dominant failure mode in the transitional regime from brittle faulting to cataclastic flow. Recent results reveal that grain size distribution plays a fundamental role in compaction band formation in this rock type. In the most homogeneous sandstones, tabular continuous bands can efficiently impact fluid flow whereas local heterogeneities make the bands more tortuous, less continuous, and in turn less efficient as permeability barrier. The stress states for compaction band formation inferred in the field are significantly lower than those measured in the laboratory data. We however show that compaction bands can develop under creep (constant stress) conditions over extended periods of time, at stresses significantly lower than reported in previous studies and hence closer to estimates based on field observations. Our creep data show that significant time-dependent compaction can be expected in sandstone at stress conditions beyond the yield point. The three damage proxies recorded during our triaxial experiments show an obvious correlation, suggesting that the mechanism leading to this time-dependent compaction is stress corrosion cracking.
While convincing field observations of compaction bands were presented in carbonate formations, experimental studies gave so far contrasted results, suggesting that conditions for compaction band development in limestone may be different than in sandstone. It has been noted that local heterogeneities, material properties and geometric effects may favour or inhibit the formation of compaction bands in porous carbonates. Our recent results based on X-ray computed microtomography suggest that the degree of cementation plays a fundamental role on the development of compaction localization in carbonate formations.
Bio : Parick Baud is currently Professor of Geophysics at EOST Strasbourg. He is in charge of the Rock Physics, Petrophysics, Hydrology, borehole Geophysics and Fracture & Fluid Mechanics courses. In 2008 he was invited professor at COPPE/Universitade Federal of Rio de Janeiro. He got his PhD in 1995 for his thesis : "Theoretical and experimental study of crustal rock fracturing". His current researches are Rock Mechanics and Rock Physics with focus on energy resources, environmental applications and natural hazards. Study of both the phenomenological and micromechanical aspects of rock deformation and fluid flow, using an approach integrating high-pressure experiment, characterization of microstructure and theoretical analysis.
Recent topics: Compaction bands in porous sandstone, time-dependent deformation in rocks, p hysical properties and damage in volcanic rocks: implications for the dynamics on active volcanoes, dilatancy, compaction, failure and fluid flow in carbonate rocks X-ray Computed Microtomography. 63 papers, h index 26(SCOPUS)
RECENT PUBLICATIONS
Zhu, W., P. Baud, S. Vinciguerra, and T.-f. Wong, Micromechanics of brittle faulting and cataclastic flow in Mount Etna basalt, J. Geophys. Res. Solid Earth, 121, doi:10.1002/2016JB012826, 2016.
Baud, P., T. Reuschlé, Y. Ji, C. Cheung, and T.-f. Wong, Mechanical compaction and strain localization in Bleurswiller sandstone, J. Geophys. Res. Solid Earth, 120, doi:10.1002/2015JB012192, 2015.
Heap M.J., N. Brantut, P. Baud, and P.G. Meredith, Time-dependent compaction band formation in sandstone. J. Geophys. Res., DOI: 10.1002/2015JB012022, 2015.
Ji, Y., S. Hall, P. Baud, and T.-f. Wong, Characterization of pore structure and strain localization in Majella limestone by X-ray computed tomography and digital image correlation, Geophys. J. Int., 200, 701-719, 2015.
Recent topics: Compaction bands in porous sandstone, time-dependent deformation in rocks, p hysical properties and damage in volcanic rocks: implications for the dynamics on active volcanoes, dilatancy, compaction, failure and fluid flow in carbonate rocks X-ray Computed Microtomography. 63 papers, h index 26(SCOPUS)
RECENT PUBLICATIONS
Zhu, W., P. Baud, S. Vinciguerra, and T.-f. Wong, Micromechanics of brittle faulting and cataclastic flow in Mount Etna basalt, J. Geophys. Res. Solid Earth, 121, doi:10.1002/2016JB012826, 2016.
Baud, P., T. Reuschlé, Y. Ji, C. Cheung, and T.-f. Wong, Mechanical compaction and strain localization in Bleurswiller sandstone, J. Geophys. Res. Solid Earth, 120, doi:10.1002/2015JB012192, 2015.
Heap M.J., N. Brantut, P. Baud, and P.G. Meredith, Time-dependent compaction band formation in sandstone. J. Geophys. Res., DOI: 10.1002/2015JB012022, 2015.
Ji, Y., S. Hall, P. Baud, and T.-f. Wong, Characterization of pore structure and strain localization in Majella limestone by X-ray computed tomography and digital image correlation, Geophys. J. Int., 200, 701-719, 2015.
Practical information
- General public
- Free
Organizer
- Prof. Dr Brice Lecampion & Prof. Dr Katrin Beyer
Contact
- Prof. Dr Marie Violay