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Title: Fault structure, stress, or pressure control of the seismicity in shale? Insights from a controlled experiment of fluid-induced fault reactivation

It is clear that clay formations are present in reservoirs and earthquake faults, but questions remain on their mechanical behavior, as they can vary from ductile (aseismic) to brittle (seismic). An experiment, at a scale of 10 m, aims to reactivate a natural fault by fluid pressure in shale materials. The injection area was surrounded by a dense monitoring network comprising pressure, deformation, and seismicity sensors, in a well-characterized geological setting. Thirty-two microseismic events were recorded during several injection phases in five different locations within the fault zone. Their computed magnitude ranged between -4.3 and -3.7. Their spatiotemporal distribution, compared with the measured displacement at the injection points, shows that most of the deformation induced by the injection is aseismic. Whether the seismicity is controlled by the fault architecture, mineralogy of fracture filling, fluid, and/or stress state is then discussed. The fault damage zone architecture and mineralogy are of crucial importance, as seismic slip mainly localizes on the sealed-with-calcite fractures which predominate in the fault damage zone. As no seismicity is observed in the close vicinity of the injection areas, the presence of fluid seems to prevent seismic slips. The fault core acts as an impermeable hydraulic barrier that favorsmore » fluid confinement and pressurization. Therefore, the seismic behavior seems to be strongly sensitive to the structural heterogeneity (including permeability) of the fault zone, which leads to a heterogeneous stress response to the pressurized volume.« less
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [4] ;  [5] ;  [5] ;  [3] ;  [5] ;  [6] ;  [2] ;  [2]
  1. GEOAZUR, University of Nice Sophia-Antipolis, CNRS, IRD, Côte d'Azur Observatory (France)
  2. MAGNITUDE, Centre Regain-Route de Marseille, Sainte-Tulle (France)
  3. CEREGE, Aix-Marseille University, CNRS, IRD, Marseille (France)
  4. SITES S.A.S., Espace Européen, Ecully (France)
  5. TOTAL, Exploration and Production, Research and Development, Pau cedex (France)
  6. IRSN, Laboratoire d'Etude et de Recherche sur les Transferts et les Interactions dans les Sols, Fontenay-aux-Roses (France)
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Solid Earth
Additional Journal Information:
Journal Volume: 121; Journal Issue: 6; Journal ID: ISSN 2169-9313
Publisher:
American Geophysical Union
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES
OSTI Identifier:
1480723

De Barros, Louis, Daniel, Guillaume, Guglielmi, Yves, Rivet, Diane, Caron, Hervé, Payre, Xavier, Bergery, Guillaume, Henry, Pierre, Castilla, Raymi, Dick, Pierre, Barbieri, Ernesto, and Gourlay, Maxime. Fault structure, stress, or pressure control of the seismicity in shale? Insights from a controlled experiment of fluid-induced fault reactivation. United States: N. p., Web. doi:10.1002/2015JB012633.
De Barros, Louis, Daniel, Guillaume, Guglielmi, Yves, Rivet, Diane, Caron, Hervé, Payre, Xavier, Bergery, Guillaume, Henry, Pierre, Castilla, Raymi, Dick, Pierre, Barbieri, Ernesto, & Gourlay, Maxime. Fault structure, stress, or pressure control of the seismicity in shale? Insights from a controlled experiment of fluid-induced fault reactivation. United States. doi:10.1002/2015JB012633.
De Barros, Louis, Daniel, Guillaume, Guglielmi, Yves, Rivet, Diane, Caron, Hervé, Payre, Xavier, Bergery, Guillaume, Henry, Pierre, Castilla, Raymi, Dick, Pierre, Barbieri, Ernesto, and Gourlay, Maxime. 2016. "Fault structure, stress, or pressure control of the seismicity in shale? Insights from a controlled experiment of fluid-induced fault reactivation". United States. doi:10.1002/2015JB012633. https://www.osti.gov/servlets/purl/1480723.
@article{osti_1480723,
title = {Fault structure, stress, or pressure control of the seismicity in shale? Insights from a controlled experiment of fluid-induced fault reactivation},
author = {De Barros, Louis and Daniel, Guillaume and Guglielmi, Yves and Rivet, Diane and Caron, Hervé and Payre, Xavier and Bergery, Guillaume and Henry, Pierre and Castilla, Raymi and Dick, Pierre and Barbieri, Ernesto and Gourlay, Maxime},
abstractNote = {It is clear that clay formations are present in reservoirs and earthquake faults, but questions remain on their mechanical behavior, as they can vary from ductile (aseismic) to brittle (seismic). An experiment, at a scale of 10 m, aims to reactivate a natural fault by fluid pressure in shale materials. The injection area was surrounded by a dense monitoring network comprising pressure, deformation, and seismicity sensors, in a well-characterized geological setting. Thirty-two microseismic events were recorded during several injection phases in five different locations within the fault zone. Their computed magnitude ranged between -4.3 and -3.7. Their spatiotemporal distribution, compared with the measured displacement at the injection points, shows that most of the deformation induced by the injection is aseismic. Whether the seismicity is controlled by the fault architecture, mineralogy of fracture filling, fluid, and/or stress state is then discussed. The fault damage zone architecture and mineralogy are of crucial importance, as seismic slip mainly localizes on the sealed-with-calcite fractures which predominate in the fault damage zone. As no seismicity is observed in the close vicinity of the injection areas, the presence of fluid seems to prevent seismic slips. The fault core acts as an impermeable hydraulic barrier that favors fluid confinement and pressurization. Therefore, the seismic behavior seems to be strongly sensitive to the structural heterogeneity (including permeability) of the fault zone, which leads to a heterogeneous stress response to the pressurized volume.},
doi = {10.1002/2015JB012633},
journal = {Journal of Geophysical Research. Solid Earth},
number = 6,
volume = 121,
place = {United States},
year = {2016},
month = {6}
}