Permeability of Fractures Created by Triaxial Direct Shear and Simultaneous X-Ray Imaging Available to Purchase

Rock fractures in the subsurface have the potential to act as fluid flow pathways but the permeability of existing, new, or future in-situ rock fractures is difficult to characterize. We perform triaxial direct shear experiments to evaluate the permeability potential of freshly created fractures as a function of stress/depth using specimens of carbonate-rich Marcellus Shale. Applied confining stress ranged from 2 to 30 MPa, specimens were 25 mm diameter and 25 mm length, shearing displacement of at least 2 mm was imposed, and measured permeability ranged between 10^-3 and 10⁴ mD as dependent on stress and fracture conditions. Simultaneous X-ray video and computed tomography were used to directly measure fracture displacement and apertures. Results show that the stress at which fractures form is likely the most significant factor controlling fracture permeability, with higher stresses causing significant 2 to 4 orders of magnitude permeability reduction. The effect of creating fractures at high stress on permeability reduction was significantly stronger than the effect of increasing the confining stress on an existing fracture. Results included analysis of transient fracture permeability following renewed shear displacement, a process which resulted in rapid permeability enhancement followed by a slower decay in permeability.