Multiscale anisotropic mechanical properties of oil shale: New insights from nanoindentation profiling

作者：Zi-Geng Pei, Guanglei Cui, Yongting Duan, Yuling Tan, Derek Elsworth, Wangxing Cheng, Ningliang Sun, Zhejun Pan · 发表于：Petroleum Science · 年份：2025 · DOI：10.1016/j.petsci.2025.09.011 · 被引用次数：16 · 研究领域：Hydrocarbon exploration and reservoir analysis、Drilling and Well Engineering、Hydraulic Fracturing and Reservoir Analysis

Oil shale reservoirs are characterized by significant heterogeneity in mineral components and pronounced anisotropy in micromechanical properties—both influencing resource recovery. We couple fine-scale nanoindentation and mineral analyzer (Tescan Integrated Mineral Analyzer (TIMA)) profiling of the mechanical properties and components of oil shale samples from the Ordos Basin, China. We use an updated clustering method, including a more precise way to delineate mineral boundaries, to precisely categorize the numerous nanoindentation test data into mineral composition groups. The lowest-to-highest ranking of Young's modulus and fracture toughness values in our samples is in the order clay, quartz, feldspar, dolomite, and then pyrite. Anisotropic characteristics of each phase were determined at various scales, with values of Young's modulus and fracture toughness are higher on surfaces parallel to the bedding plane than on those perpendicular to it. The clay-rich dark phase exhibits lower Young's modulus, making its pore structures more prone to collapse during gas depletion. Conversely, the fracture toughness of the bright phase is higher than that of the dark phase, causing the hydraulic fracturing to more easily penetrate through the dark phase and stop at the bright phase boundary. These divergences in mechanical properties are caused by the microstructure of the oil shale during sedimentation: the discrete distribution of hard minerals in the bright phase constrains defor...