NG010-03
Numerical Simulation of Rock Fracture Roughness due to Mineral Layering and Texture
Wednesday, 16 December 2020: 08:38
Virtual
Chaoyi Wang1, Liyang Jiang1, Antonio Bobet2 and Laura J Pyrak-Nolte3, (1)Purdue University, Department of Physics and Astronomy, West Lafayette, IN, United States, (2)Purdue University, Lyles School of Civil Engineering, West Lafayette, IN, United States, (3)Purdue University, Department of Physics and Astronomy; Department of Earth, Atomospheric and Planetary Sciences; Lyles School of Civil Engineering, West Lafayette, IN, United States
Abstract:
A challenge in subsurface engineering is to enhance permeability through controlled fracturing. In layered rocks, corrugated tensile fractures exhibit significantly higher volumetric flow rates parallel to the corrugation ridges than perpendicular. Understanding the mechanisms that produce corrugations in rock remains a major challenge because of their heterogeneous micro-structure and inherent mineral texture. A recent laboratory study showed that mode I fracture toughness and roughness were governed by the relative orientation between layering and mineral fabric. However, the micro-mechanisms responsible for the macroscopic observations were not well understood. Here, a digital rock model was created using the distinct element method with a bonded particle model to study the influence of mineral layering and texture on fracturing. The digital model replicates the laboratory 3-point bending geometry and material properties. Mineral layers were defined by low bonding strength at the layer boundaries, while mineral texture was approximated by a periodic spatial distribution of particle bonding strength within a layer.
Simulations were conducted for a constant loading configuration on samples with different relative orientations between the layers and mineral texture. The simulated fracture toughness and roughness were found to match the laboratory tests. The simulations show that alignment of an elongated mineral texture perpendicular to the loading direction, generates surfaces with large asperity height and exhibit corrugations. Mineral textures with a wide distribution of bonding strengths lead to rougher fractures and a reduced fracture toughness. This study provides a novel means to predict fracture properties from simulation of detailed mineralogical information, and is a potential tool for designing enhanced flow in fractures in layered rock.
Acknowledgments: The authors acknowledge support of this work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Geosciences Research Program under Award Number (DE-FG02-09ER16022). This material was based upon work supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE), Office of Technology Development, Geothermal Technologies Office.
