Time-Resolved In Situ Imaging of Strain Localization in Draupne Shale under Triaxial Compression

• DOI: 10.1103/physrevapplied.20.034046
• Publication Date: 2023-09-20T15:08:01Z
• Authors: Aldritt Scaria Ma...; Kim Robert Tekseth; Fredrik K. Mürer; Benoît Cordonnier; Nicolaine Agofack; Jessica McBeck; Pierre Cerasi; François Renard; Basab Chattopadhyay; Dag W. Breiby
• Keywords: Caprock

Understanding the mechanical behavior of rocks is crucial in subsurface activities, including storage carbon dioxide and hydrogen gases, which both rely on shale caprocks as potential sealing barriers. Several current large-scale initiatives focus North Sea aquifers. The Draupne Formation contains a series layers interbedded with sandstone layers, overall thickness varies range from tens to hundreds meters. Injection into underlying reservoirs leads changes surrounding stress field, can result fault reactivation or creation microfractures, thus, alter performance caprock. Time-resolved microcomputed tomography (4D $\text{\ensuremath{\mu}}$CT) has, recent years, become powerful technique for studying properties under conditions similar those prevailing geological reservoirs. Here, we present results experiments performed using triaxial rig combined 4D $\text{\ensuremath{\mu}}$CT based synchrotron radiation. Detailed analysis datasets by digital volume correlation reveals three-dimensional pattern temporally evolving deformation field. Intermittent bursts at different locations within specimen are observed, eventually evolve major fracture plane extending laterally across whole sample. This study suggests that pseudolinear-elastic-appearing macroscopic stress-strain relationship previously reported samples could consist irreversible processes occurring various weak points combination imaging strain enables situ investigations via quantification shear volumetric strains sample, thus providing an improved understanding dynamics shales.