An original approach to the problem of chemo-mechanical characterization of shale rocks is presented, which consists of combining grid nanoindentation technique, scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDS), and multispectral image analysis. X-ray microanalysis of the major elements is performed over the indented region, resulting in high-resolution images of the spatial distribution of different elements over the indentation grid. The individual elemental maps of the image fields are mathematically merged to create a multispectral image proper for segmentation into distinct clustered phases and mapped on the indentation points. Unsupervised clustering analysis is performed on the multispectral image to determine the number of statistically definable mutually exclusive material phases.

The method is illustrated through application to two types of shale rocks, demonstrating spatially varying microstructures as a result of exposure to reactive environments. Mancos shale subjected to water at ambient pressure and temperature, and Eagle Ford shale exposed to CO₂-rich brine at high pressure and high temperature conditions. Clay-, carbonate-, and feldspar-rich phases in the Mancos shale show sensitivity to water exposure, demonstrating alterations in mechanical or compositional properties compared to similar phases in unreacted samples. Carbonate-rich phases in the Eagle Ford shale show three different regions of mechanical properties: dissolution region, followed by precipitation and no reaction regions. A discussion of chemical reactions responsible for mechanical variations in different material phases is included. The results show that the method is capable of successfully isolating different material phases at the indentation scale; thus, providing an efficient means to link chemical and microstructural properties to the mechanical response.

提出了解决页岩岩石化学力学表征问题的原始方法，该方法包括结合网格纳米压痕技术，扫描电子显微镜-能量色散X射线光谱法（SEM-EDS）和多光谱图像分析。对主要元素的X射线微分析在压痕区域上进行，从而得到压痕网格上不同元素的空间分布的高分辨率图像。图像场的各个元素图在数学上合并在一起，以创建适合于分割为不同聚类相位的多光谱图像，并将其映射到凹痕点上。对多光谱图像执行无监督聚类分析，以确定统计上可定义的互斥物质相的数量。

通过应用到两种类型的页岩中来说明该方法，该方法展示了由于暴露于反应性环境而在空间上变化的微观结构。Mancos页岩在环境压力和温度下会受到水的侵蚀，Eagle Ford页岩会暴露于CO ₂在高压和高温条件下富含盐水。曼科斯页岩中富含粘土，碳酸盐和长石的相显示出对水暴露的敏感性，与未反应样品中的类似相相比，表明了机械或成分性质的变化。Eagle Ford页岩中富含碳酸盐的相显示出三个不同的机械性能区域：溶解区域，然后是沉淀区域，没有反应区域。包括引起不同材料相机械变化的化学反应的讨论。结果表明，该方法能够成功地在压痕规模下分离出不同的材料相。因此，提供了一种有效的手段将化学和微结构特性与机械响应联系起来。