Authors:

Ozan Altuntas

Date Created:

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About Paper:

Many subsurface engineering applications such as geothermal energy production rely on the connectivity of fracture networks that depends on how fractures intersect. Two outstanding questions are how two fractures intersect and what determines the void geometry of the intersection that ultimately controls connectivity. Here, we study the induced fracture propagation path in analogue rock samples that contain a single pre-existing fracture and the subsequent intersection geometry that is formed. X-ray computed tomography is used to non- destructively observe and characterize fracture intersection formation and geometry (i.e. void space, contact area). Three-point bending (3PB) tests were performed in a Deben CT5000 in-situ uniaxial stress rig in a 3D X- Ray Microscope (Zeiss Xradia 510 Versa) to enable 2D X-ray imaging of 3-D printed gypsum (3D Systems, ProJet CJP 360, layer thickness 100 µm) and alumina (Formlabs, Form 3, layer thickness 50 µm) samples during failure. The geometry of the samples was designed to determine if an intersection would preferentially occur in void regions or contact areas of the pre-existing fracture. 3D X-ray scans were also performed prior to and after the 3PB tests to provide 3D reconstructions of the intersection region. The effect of pre-existing fractures versus an array of cracks, and mixed mode loading on intersection geometry were also examined. The results of this study will aid the development of numerical methods to predict fracture intersections geometry based on stress at the crack tip of fractures, the structure of pre-existing fractures and intersection angle. Keywords: Geophysics; Additive Manufacturing; X-Ray Computed Tomography; Fracture Intersections; 3-Point Bending Test

Source:

Purdue University / 2024

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No topics listed

Co-authors:

Ozan Altuntas