Comparison of the microfracture localization in granite between fracturation and slip of a preexisting macroscopic healed joint by acoustic emission measurements

Jouinaux, Laurence; Masuda, Koji; Lei, Xinglin; Nishizawa, Osamu; Kusunose, Kazuhiro; Liu, Liqiang; Ma, Wentao

doi:10.1029/2000jb900411

Cited by 26 publications

(16 citation statements)

References 40 publications

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“…Macroscopic failure of the sample occurred when the applied differential stress reached 439 MPa, close to the strength under similar conditions of the intact granite host rock (e.g., Jouniaux et al 2001). The transducers recorded AEs during the loading experiment.…”

Section: Methodsmentioning

confidence: 99%

“…The internal structure of the rock sample was imaged by X-ray CT before and after the loading experiment, using the method of Jouniaux et al (2001). I used a conventional medical X-ray CT scanning system to obtain images of a scanned volume 160 mm in diameter in slices perpendicular to the sample axis; each slice was 1.0 mm thick and divided into a 512 × 512 voxel grid.…”

Section: Methodsmentioning

confidence: 99%

“…At laboratory scale, Lockner et al (1991) and Lockner (1993) investigated the evolution of acoustic emissions (AEs) in time and space and showed that AE clusters characterize the development of fault zones in intact rocks. Many earlier works have studied the effect of heterogeneity in a rock sample on failure processes (e.g., Lei et al 2004;Jouniaux et al 2001). These previous works show that precursory anomalies related to rock fracture are strongly dependent on the heterogeneity of the rock sample.…”

Section: Introductionmentioning

confidence: 99%

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Laboratory evidence of strength recovery of a healed fault: implications for a mechanism responsible for creating wide fault zones

Masuda

2015

Earth Planet Sp

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Fault zones consist of a high-strain fault core and a surrounding damage zone of highly fractured rock. The close, reciprocal relationship between fault zones and earthquake rupture evolution demands better understanding of the processes that create and modify damage zones. This study modeled the evolution of a damage zone in the laboratory by monitoring seismic signals (acoustic emissions) in a specimen of ultramylonite stressed to failure. The result provided evidence supporting the strength recovery of parts of the healed surface. A new fault initiated in an area of heterogeneous structure a short distance from the preexisting fault plane. Repeated cycles of fracture and healing may be one mechanism responsible for wide fault zones with multiple fault cores and damage zones.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Laboratory evidence of strength recovery of a healed fault: implications for a mechanism responsible for creating wide fault zones

Masuda

2015

Earth Planet Sp

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“…In hard rocks, fracture healing is associated with the development of physico-chemical processes such as pressure solution (Yasuhara et al 2004), a mechanism with slower kinetics compared with the development of creep deformation in soft rocks. Jouniaux et al (2001) showed that the presence of healed fractures in a rock mass lowers its mechanical strength and that the acoustic emissions recorded in a triaxial test concentrate along these healed fractures. Kim et al (2007) studied the influence of fracture statistics on the mechanical behaviour of rock masses.…”

Section: Repositories In Hard Rock Formationsmentioning

confidence: 99%

“…For a review of these aspects, the reader can refer to Guéguen & Boutéca (2004, chapter 7). Fracture nucleation and propagation in hard rocks can be imaged by means of acoustic emission recording, taking advantage of faster technologies available for signal processing and waveform analysis (Lockner et al 1991;Butt & Calder 1998;Jouniaux et al 2001;Schubnel et al 2006b). Stress-induced damage in hard rocks can be estimated indirectly from the variation of elastic-wave velocities (Takemura & Oda 2005), an important point when monitoring issues have to be addressed.…”

Section: Repositories In Hard Rock Formationsmentioning

confidence: 99%

Rock physics and geomechanics in the study of reservoirs and repositories

David

Ravalec-Dupin

2007

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Reservoir management for hydrocarbon extraction and repositories design for radioactive waste storage are two different areas in which rock physics and geomechanics provide valuable information. Although the targets and objectives are different, similar approaches and common attributes exist in both fields: safety assessment, short-to long-term prediction, integration of various scales of investigation, and remote monitoring, among others. Nevertheless, there are also important differences: reservoirs at depth are investigated through remote geophysical studies, well-logging and/or core samples retrieval, whereas direct access to repositories is possible through excavation in the host formation in which underground research laboratories can be constructed. We review a number of studies focusing on geomechanics and rock physics applied to the characterization of reservoirs and repositories, including laboratory experiments and predictive models, at different scales.Reservoir management and assessment of repository performance require the integration of different fields in Earth sciences, including geochemistry, geophysics, structural geology, and, in the case of interest here, rock physics and geomechanics. We present recent advances in the studies of reservoirs and repositories with the aim of emphasizing how rock physics and geomechanics help to obtain a better insight into important issues linked to reservoir management for exploitation of natural resources, and to repository safety assessment for hazardous waste storage in the geological environment.In the area of reservoir management, the importance of geomechanics in problems such as wellbore stability, hydraulic fracturing and subsidence is well known. Recently, there has been a growing interest in the development of a link between fluid flow simulators and geomechanical models. Several approaches have been proposed to incorporate the correct physics and to account for physical phenomena usually neglected in reservoir simulation. New techniques developed in laboratory studies provide relevant data for this integration. The approaches differ in the degree of coupling. The stronger the coupling, the more computationally demanding the simulation. Numerical experiments showed that coupling is of interest for poorly consolidated reservoirs such as chalk reservoirs. In other cases, one may wonder whether a more accurate modelling of production processes justifies the required computation cost. Complementary sensitivity studies have to be performed to better estimate the conditions in which the coupling is worthwhile.In the area of underground waste storage, the key issue is to design a repository as safe as possible for human activity and for the environment at the near surface, on time scales of the order of hundreds of years. This challenging task requires us to identify favourable geological targets for the storage, and to develop extensive scientific research in different fields, so as to obtain eventually a predictive model of the repository evolu...

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Microscale modeling of fluid flow‐geomechanics‐seismicity: Relationship between permeability and seismic source response in deformed rock joints

2014

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Key Points:• Hydro-mechanical-seismic modeling is applied to model joints behavior • Nonshear displacement affects transport and seismic behavior of joints • Confining pressure affects transport and seismic behavior of joints Supporting Information:• Readme • Figure S1 • Figure S2 • Figure S3 • tkdensityCase6 Abstract Studying rock joint deformation including both slippage and opening mechanisms provides an opportunity to investigate the connection between the permeability and seismic source mechanisms. A microscale fluid flow-geomechanics-seismicity model was built to evaluate the transport response and failure mechanism of microcracks developed along a joint in Berea sandstone samples during deformation. The modeling method considers comprehensive grain-cement interactions. Fluid flow behavior is obtained through a realistic network model of the pore space in the compacted assembly. The geometric description of the complex pore structure is characterized to predict permeability of the rock sample as a function of rock deformation by using a dynamic pore network model. As a result of microcracks development, forces and displacements in grains involved in bond breakage are measured to determine seismic moment tensor. Shear and nonshear displacements are applied to the joint samples to investigate their effects on permeability evolution and failure mechanism of microcracks during joint deformation. In addition, the effect of joint roughness is analyzed by performing numerical compression tests. We also investigate how confining pressure affects volumetric deformation leading to opening or closure of developed microcracks and permeability changes of samples with joints.

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Comparison of the microfracture localization in granite between fracturation and slip of a preexisting macroscopic healed joint by acoustic emission measurements

Cited by 26 publications

References 40 publications

Laboratory evidence of strength recovery of a healed fault: implications for a mechanism responsible for creating wide fault zones

Laboratory evidence of strength recovery of a healed fault: implications for a mechanism responsible for creating wide fault zones

Rock physics and geomechanics in the study of reservoirs and repositories

Microscale modeling of fluid flow‐geomechanics‐seismicity: Relationship between permeability and seismic source response in deformed rock joints

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