Synchrotron 4D X-Ray Imaging Reveals Strain Localization at the Onset of System-Size Failure in Porous Reservoir Rocks

Abstract Understanding the mechanisms of strain localization leading to brittle failure in reservoir rocks can shed light on geomechanical processes such as porosity and permeability evolution during rock deformation, induced seismicity, fracturing, subsidence geological reservoirs. We perform triaxial compression tests three types porous reveal local deformation that control system-size failure. deformed cylindrical samples Adamswiller sandstone (23% porosity), Bentheim Anstrude limestone (20% using an X-ray transparent apparatus. This apparatus enables acquisition three-dimensional synchrotron images, under situ stress conditions. Analysis tomograms provide 3D distributions microfractures dilatant pores from which we calculated evolving macroporosity. Digital volume correlation analysis reveals dominant by providing incremental components pairs tomograms. In types, damage localized a single shear band or formation conjugate bands at The closely matches dilation, contraction, shear. With increasing confinement, sandstones shifts dilative (Bentheim sandstone) contractive (Adamswiller sandstone). Our study also links compactive with variations limestone, is characterized complex pore geometry. Scanning electron microscopy images indicate microscale guiding are collapse grain crushing sandstones, collapse, pore-emanated fractures cataclasis limestones. dynamic microtomography data brings unique insights between evolutions microstructure, evolution, macroscopic approach rocks.