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Title: Field characterization of elastic properties across a fault zone reactivated by fluid injection

In this paper, we studied the elastic properties of a fault zone intersecting the Opalinus Clay formation at 300 m depth in the Mont Terri Underground Research Laboratory (Switzerland). Four controlled water injection experiments were performed in borehole straddle intervals set at successive locations across the fault zone. A three-component displacement sensor, which allowed capturing the borehole wall movements during injection, was used to estimate the elastic properties of representative locations across the fault zone, from the host rock to the damage zone to the fault core. Young's moduli were estimated by both an analytical approach and numerical finite difference modeling. Results show a decrease in Young's modulus from the host rock to the damage zone by a factor of 5 and from the damage zone to the fault core by a factor of 2. In the host rock, our results are in reasonable agreement with laboratory data showing a strong elastic anisotropy characterized by the direction of the plane of isotropy parallel to the laminar structure of the shale formation. In the fault zone, strong rotations of the direction of anisotropy can be observed. Finally, the plane of isotropy can be oriented either parallel to bedding (when few discontinuitiesmore » are present), parallel to the direction of the main fracture family intersecting the zone, and possibly oriented parallel or perpendicular to the fractures critically oriented for shear reactivation (when repeated past rupture along this plane has created a zone).« less
Authors:
ORCiD logo [1] ; ORCiD logo [1] ;  [1] ;  [2] ;  [1]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Energy Geoscience Division
  2. Federal Office of Topography (Swisstopo), Wabern (Switzerland)
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Solid Earth
Additional Journal Information:
Journal Volume: 122; Journal Issue: 8; Journal ID: ISSN 2169-9313
Publisher:
American Geophysical Union
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Federal Office of Topography (Swisstopo), Wabern (Switzerland)
Sponsoring Org:
USDOE Office of Fossil Energy (FE)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; fault zone; elastic properties; claystone formation; High Pulse Poroelasticity Probe
OSTI Identifier:
1436338
Alternate Identifier(s):
OSTI ID: 1376761

Jeanne, Pierre, Guglielmi, Yves, Rutqvist, Jonny, Nussbaum, Christophe, and Birkholzer, Jens. Field characterization of elastic properties across a fault zone reactivated by fluid injection. United States: N. p., Web. doi:10.1002/2017JB014384.
Jeanne, Pierre, Guglielmi, Yves, Rutqvist, Jonny, Nussbaum, Christophe, & Birkholzer, Jens. Field characterization of elastic properties across a fault zone reactivated by fluid injection. United States. doi:10.1002/2017JB014384.
Jeanne, Pierre, Guglielmi, Yves, Rutqvist, Jonny, Nussbaum, Christophe, and Birkholzer, Jens. 2017. "Field characterization of elastic properties across a fault zone reactivated by fluid injection". United States. doi:10.1002/2017JB014384. https://www.osti.gov/servlets/purl/1436338.
@article{osti_1436338,
title = {Field characterization of elastic properties across a fault zone reactivated by fluid injection},
author = {Jeanne, Pierre and Guglielmi, Yves and Rutqvist, Jonny and Nussbaum, Christophe and Birkholzer, Jens},
abstractNote = {In this paper, we studied the elastic properties of a fault zone intersecting the Opalinus Clay formation at 300 m depth in the Mont Terri Underground Research Laboratory (Switzerland). Four controlled water injection experiments were performed in borehole straddle intervals set at successive locations across the fault zone. A three-component displacement sensor, which allowed capturing the borehole wall movements during injection, was used to estimate the elastic properties of representative locations across the fault zone, from the host rock to the damage zone to the fault core. Young's moduli were estimated by both an analytical approach and numerical finite difference modeling. Results show a decrease in Young's modulus from the host rock to the damage zone by a factor of 5 and from the damage zone to the fault core by a factor of 2. In the host rock, our results are in reasonable agreement with laboratory data showing a strong elastic anisotropy characterized by the direction of the plane of isotropy parallel to the laminar structure of the shale formation. In the fault zone, strong rotations of the direction of anisotropy can be observed. Finally, the plane of isotropy can be oriented either parallel to bedding (when few discontinuities are present), parallel to the direction of the main fracture family intersecting the zone, and possibly oriented parallel or perpendicular to the fractures critically oriented for shear reactivation (when repeated past rupture along this plane has created a zone).},
doi = {10.1002/2017JB014384},
journal = {Journal of Geophysical Research. Solid Earth},
number = 8,
volume = 122,
place = {United States},
year = {2017},
month = {8}
}