纳米压痕
微尺度化学
材料科学
微观力学
油页岩
复合材料
表征(材料科学)
矿物学
水银孔隙仪
微观结构
多孔性
复合数
地质学
纳米技术
多孔介质
数学教育
古生物学
数学
作者
Yuriy Veytskin,Vamsi K. Tammina,Christopher P. Bobko,Patrick G. Hartley,M.B. Clennell,David N. Dewhurst,Raymond R. Dagastine
标识
DOI:10.1016/j.gete.2016.10.004
摘要
Shales are heterogeneous sedimentary rocks which typically comprise a variable mineralogy (including compacted clay particles sub-micrometer in size), silt grains, and nanometer sized pores collectively arranged with transversely isotropic symmetry. A detailed understanding of the micro- and sub-microscale geomechanics of these minerals is required to improve models of shale strength and stiffness properties. In this paper, we propose a linked experimental–computational approach and validate a combination of grid nanoindentation and Scanning Electron Microscopy (SEM) with Energy and Wavelength Dispersive X-ray Spectrometry (EDS/WDS) at the same spatial locations to identify both the nano-mechanical morphology and local mineralogy of these nanocomposites. The experimental parameters of each method are chosen to assess a similar volume of material. By considering three different shales of varying mineralogy and mechanical diversity, we show through the EMMIX statistical iterative technique that the constituent phases, including highly compacted plate- or sheet-like clay particles, carbonates, silicates, and sulfides, have distinct nano-mechanical morphologies and associated indentation moduli and hardness. Nanoindentation-based strength homogenization analysis determines an average clay packing density, friction coefficient, and solid cohesion for each tested shale sample. Comparison of bulk to microscale geomechanical properties, through bulk porosimetry measurements, reveals a close correspondence between bulk and microscale clay packing densities. The determination of mechanical microstructure and material properties is useful for predictive microporomechanical models of the stiffness and strength properties of shale. The experimental and computational approaches presented here also apply to other chemically and mechanically complex materials exhibiting nanogranular, composite behavior.
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