The Sealing Mechanisms of a Fracture in Opalinus Clay as Revealed by in situ Synchrotron X-Ray Micro-Tomography

Voltolini, Marco; Ajo‐Franklin, Jonathan

doi:10.3389/feart.2020.00207

Cited by 24 publications

(22 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our experiments show that swelling induced self‐sealing process in the presence of an aqueous fluid drives the heterogeneous permeability changes and creates dynamic hydraulic pathways like those observed in the field (Jeanne et al., 2018). Experimental work has recently shown that CO 2 and CO 2 saturated brine produces a similar swelling behavior (Voltolini & Ajo‐Franklin, 2020). Therefore, caprocks that have high swelling clay content would be less prone to leakage of CO 2 saturated brine.…”

Section: Implications For Subsurface Engineering In Claystones and Shmentioning

confidence: 91%

Chemo‐Mechanical Coupling in Fractured Shale With Water and Hydrocarbon Flow

Wenning

Madonna

Kurotori

et al. 2021

Geophysical Research Letters

View full text Add to dashboard Cite

The transport of chemically reactive fluids through fractured clay‐rich rocks is fundamental to many subsurface engineering technologies. Here, we present results of direct‐shear laboratory experiments with simultaneous imaging by X‐ray Computed Tomography in Opalinus claystone with subsequent fluid injection to unravel the interplay between mechanical fracture deformation, fluid sorption, and flow. Under constant radial stress (σc = 1.5 MPa), the average mechanical aperture trued¯CT increases with shear displacement. Upon brine injection, trued¯CT is reduced by 40% relative to initial conditions (trued¯CT0=140−250 μm) and fluid‐sorption induces a divergent displacement of the two sample halves (Δh = ±50 − 170 μm) quantified by digital image correlation. None of these changes are observed in a control experiment with decane, indicating that creep is subordinate to swelling in sealing the fracture. Swelling‐induced changes in permeability within the fracture are heterogeneous and largely affect the fracture flow field, as computed using numerical simulations.

show abstract

Section: Implications For Subsurface Engineering In Claystones and Shmentioning

confidence: 91%

Chemo‐Mechanical Coupling in Fractured Shale With Water and Hydrocarbon Flow

Wenning

Madonna

Kurotori

et al. 2021

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…processes investigated in a sample, which has been experimentally deformed up to peak stress, partly resemble those observed in naturally deformed OPA. Furthermore, the influence of strain amount and strain rate, pore pressure evolution during deformation, pressure solution, and mineral precipitation as well as self-sealing plays an important role (Laurich et al, 2018;Voltolini and Ajo-Franklin, 2020).…”

Section: Damage Accumulation During Compressive Loadingmentioning

confidence: 99%

“…The deformation behaviour of shales or clay-rich materials can be brittle, ductile, or a combination of both. Underlying micromechanisms are cataclasis, granular flow, frictional sliding, and crystal plasticity (Morgenstern and Tchalenko, 1967;Handin et al, 1963;Maltman, 1987;Logan et al, 1979Logan et al, , 1987Wang et al, 1980;Lupini et al, 1981;Rutter et al, 1986;Blenkinsop, 2000;Desbois et al, 2016Desbois et al, , 2017Schuck et al, 2020). Additionally, Ibanez and Kronenberg (1993) distinguished deformation modes based on the loading direction with respect to bedding.…”

Section: Introductionmentioning

confidence: 99%

Micromechanisms leading to shear failure of Opalinus Clay in a triaxial test: a high-resolution BIB–SEM study

et al. 2021

View full text Add to dashboard Cite

Abstract. A microphysics-based understanding of mechanical and hydraulic processes in clay shales is required for developing advanced constitutive models, which can be extrapolated to long-term deformation. Although many geomechanical tests have been performed to characterise the bulk mechanical, hydro-mechanical, and failure behaviour of Opalinus Clay, important questions remain about micromechanisms: how do microstructural evolution and deformation mechanisms control the complex rheology? What is the in situ microstructural shear evolution, and can it be mimicked in the laboratory? In this contribution, scanning electron microscopy (SEM) was used to image microstructures in an Opalinus Clay sample deformed in an unconsolidated–undrained triaxial compression test at 4 MPa confining stress followed by argon broad ion beam (BIB) polishing. Axial load was applied (sub-)perpendicular to bedding until the sample failed. The test was terminated at an axial strain of 1.35 %. Volumetric strain measurements showed bulk compaction throughout the compression test. Observations on the centimetre to micrometre scale showed that the samples exhibited shear failure and that deformation localised by forming a network of micrometre-wide fractures, which are oriented with angles of 50∘ with respect to horizontal. In BIB–SEM at the grain scale, macroscale fractures are shown to be incipient shear bands, which show dilatant intergranular and intragranular microfracturing, granular flow, bending of phyllosilicate grains, and pore collapse in fossils. Outside these zones, no deformation microstructures were observed, indicating only localised permanent deformation. Thus, micromechanisms of deformation appear to be controlled by both brittle and ductile processes along preferred deformation bands. Anastomosing networks of fractures develop into the main deformation bands with widths up to tens of micrometres along which the sample fails. Microstructural observations and the stress–strain behaviour were integrated into a deformation model with three different stages of damage accumulation representative for the deformation of the compressed Opalinus Clay sample. Results on the microscale explain how the sample locally dilates, while bulk measurement shows compaction, with an inferred major effect on permeability by an increase in hydraulic conductivity within the deformation band. Comparison with the microstructure of highly strained Opalinus Clay in fault zones shows partial similarity and suggests that during long-term deformation additional solution–precipitation processes operate.

show abstract

“…Studying mechanisms of rock failure is important to better understand hydraulic fracturing but we did not find studies utilizing real-time 3D imaging as a routine tool. Voltolini & Ajo-Franklin (2020a) show a fracture sealing mechanism in clay, revealed by in situ 3D imaging at a rate of $ 14 min for one full scan. An important process of evolution of propped fractures in shale was imaged only at a rate of $ 10 min for one full scan (Voltolini & Ajo-Franklin, 2020b); fracture development caused by the freeze-thaw cycling of porous samples was imaged at a rate of 1.3 min for one scan (De Kock et al, 2015).…”

Section: Introductionmentioning

confidence: 95%

Real-time streaming tomographic reconstruction with on-demand data capturing and 3D zooming to regions of interest

Никитин¹,

Tekawade²,

Duchkov³

et al. 2022

J Synchrotron Rad

View full text Add to dashboard Cite

Complex dynamic tomographic experiments at brilliant X-ray light sources require real-time feedback on the sample changes with respect to environmental conditions, selecting representative regions of interest for high-resolution scanning, and on-demand data saving mechanisms for storing only relevant projections acquired by fast area detectors and reducing data volumes. Here the implementation details of a 3D real-time imaging monitoring instrument, with zooming to a volume of interest with easy-to-use visualization via ImageJ, a tool familiar to most beamline users, is presented. The instrument relies on optimized data flow between the detector and processing machines and is implemented on commodity computers. The instrument has been developed at beamline 2-BM of the Advanced Photon Source, where the automatic lens changing mechanism for zooming is implemented with an Optique Peter microscope. Performance tests demonstrate the ability to process more than 3 GB of projection data per second and generate real-time 3D zooming with different magnification. These new capabilities are essential for new APS Upgrade instruments such as the projection microscope under development at beamline 32-ID. The efficacy of the proposed instrument was demonstrated during an in situ tomographic experiment on ice and gas hydrate formation in porous samples.

show abstract

The Sealing Mechanisms of a Fracture in Opalinus Clay as Revealed by in situ Synchrotron X-Ray Micro-Tomography

Cited by 24 publications

References 41 publications

Chemo‐Mechanical Coupling in Fractured Shale With Water and Hydrocarbon Flow

Chemo‐Mechanical Coupling in Fractured Shale With Water and Hydrocarbon Flow

Micromechanisms leading to shear failure of Opalinus Clay in a triaxial test: a high-resolution BIB–SEM study

Real-time streaming tomographic reconstruction with on-demand data capturing and 3D zooming to regions of interest

Contact Info

Product

Resources

About