The mechanical properties of the constituent minerals in shale rock are fundamental to a better knowledge of multi-scale shale behaviors. It benefits the engineering applications and predictive physics modeling of the shale formation. In this work, nanoindentation testing combined with scanning electron microscopy - energy dispersive spectroscopy (SEM-EDS) were used to obtain the in situ mechanical properties of individual mineral phases in four shale samples. Engraved cross-marks were employed to locate the indented areas on a micron scale for subsequent SEM-EDS measurements and analysis. The elastic moduli and hardness of the quartz, iron-type minerals, muscovite, clinochlore, organic matter, and the mineral assortments in the matrix were analyzed and relevant deformative behaviors were compared. Results show that the identified mineral groups exhibit a diverse set of mechanical properties at the nanoscale. The iron-type minerals have the highest elastic modulus (104.7 GPa), then followed by quartz, muscovite, clinochlore, and organic matter. Quartz shows the highest hardness (10.2 GPa). The identified minerals demonstrated different elasto-plastic characteristics to the indentation loads. Quartz exhibits the lowest plastic behavior, while phyllosilicates exhibited large plastic behavior owing to the layered structure. Organic matter showed both elastic-dominant and plastic-dominant behaviors, which may be related to the chemical compositional differences and various thermal maturity of kerogen in the shale samples. The mechanical properties of three mineral assortments in shale matrices vary significantly due to the wide variety of the mineral compositions. Radial cracks were observed on the boundary of brittle minerals and relatively weak minerals, while shear cracks were observed on strength-weak minerals such as layered silicates and organic matters. The mechanism of the induced cracks was discussed. This study obtains a basic understanding of shale behavior on nano-scale and provides reliable basic data for multi-scale modeling of shale reservoirs without the need for large-scale mechanical tests.

页岩中组成矿物的力学性质是更好地了解多尺度页岩行为的基础。它有利于页岩地层的工程应用和预测物理建模。在这项工作中，纳米压痕测试结合扫描电子显微镜 -能量色散光谱 (SEM-EDS) 用于获得四个页岩样品中单个矿物相的原位力学性能。雕刻的十字标记用于在微米尺度上定位缩进区域，用于随后的 SEM-EDS 测量和分析。石英、铁类矿物、白云母、斜绿石的弹性模量和硬度、有机质和基质中的矿物组合进行了分析，并比较了相关的变形行为。结果表明，已确定的矿物组在纳米尺度上表现出多种机械性能。铁类矿物的弹性模量最高（104.7 GPa），其次是石英、白云母、斜绿石和有机质。石英的硬度最高（10.2 GPa）。识别出的矿物对压痕载荷表现出不同的弹塑性特征。石英表现出最低的塑性行为，而层状硅酸盐由于层状结构而表现出较大的塑性行为。有机质同时表现出弹性为主和塑性为主的行为，这可能与化学成分的差异和多种因素有关。页岩样品中干酪根的热成熟度。由于矿物成分的多样性，页岩基质中三种矿物组合的机械性能差异很大。在脆性矿物和相对弱矿物的边界上观察到径向裂纹，而在层状硅酸盐和有机质等强度弱矿物的边界上观察到剪切裂纹。讨论了诱发裂纹的机理。本研究获得了对纳米尺度页岩行为的基本认识，为页岩储层的多尺度建模提供了可靠的基础数据，无需进行大规模力学试验。