The full set of transversely isotropic elastic stiffness constants of inorganic shale (mudrock with total organic carbon less than 1.5%) can be successfully modeled and, therefore, predicted based on the mineral composition, mineral stiffnesses, clay platelet orientation distribution function, and microgeometry of the pore space. A fundamentally novel concept drawing from the Maxwell homogenization scheme allows a zero-porosity mineral matrix of the mudrock to be expressed as a polycrystal of variable composition and clay mineral alignment. Introduction of the brine-saturated pore space allows us to account for realistic 3D pore types and their combinations as well as elastic interactions, opening the way for better integration of rock physics and geomechanics with modern petrographic investigations and better shale velocity/anisotropy prediction as a function of diagenetic porosity reduction. We were able to calibrate the model using a limited subset of high-quality ultrasonic measurements on shale and constrain main pore geometries such as tetrahedra and irregular spheroids, often reported in modern scanning electron microscopy images. The model is then used to constrain the anisotropy tensor elements of illite-dominated clay, impossible to measure directly, and explore the main compositional and microstructural controls on the anisotropic elasticity of inorganic shale, including the most troublesome $C_{13}$ stiffness and its derivative — the anisotropy parameter $\delta$, which is of paramount importance in quantitative seismic interpretation.

中文翻译：

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基于微力学的无机页岩岩石物理模型

可以成功地建模完整的无机页岩（有机碳总量小于1.5％的泥岩）的横观各向同性弹性刚度常数，因此可以基于矿物组成，矿物刚度，粘土片晶取向分布函数和矿物的微观几何结构进行预测。孔隙空间。麦克斯韦均质化方案从根本上新颖的概念图允许将泥岩的零孔隙度矿物基质表达为组成和粘土矿物排列可变的多晶。引入盐水饱和的孔隙后，我们就可以考虑逼真的3D孔隙类型及其组合以及弹性相互作用，为更好地将岩石物理学和地质力学与现代岩石学研究相结合，并根据成岩孔隙度的降低更好地控制页岩速度/各向异性，开辟了道路。我们能够在页岩上使用高质量超声波测量的有限子集来校准模型，并约束主要孔隙几何形状（例如四面体和不规则球体），这在现代扫描电子显微镜图像中经常出现。然后使用该模型来约束伊利石为主的粘土的各向异性张量元素（无法直接测量），并探索对无机页岩各向异性弹性的主要组成和微观结构控制，包括最麻烦的 我们能够在页岩上使用高质量超声波测量的有限子集来校准模型，并约束主要孔隙几何形状（例如四面体和不规则球体），这在现代扫描电子显微镜图像中经常出现。然后使用该模型来约束伊利石为主的粘土的各向异性张量元素（无法直接测量），并探索对无机页岩各向异性弹性的主要组成和微观结构控制，包括最麻烦的 我们能够在页岩上使用高质量超声波测量的有限子集来校准模型，并约束主要孔隙几何形状（例如四面体和不规则球体），这在现代扫描电子显微镜图像中经常出现。然后使用该模型来约束伊利石为主的粘土的各向异性张量元素（无法直接测量），并探索对无机页岩各向异性弹性的主要组成和微观结构控制，包括最麻烦的$C_{13}$ 刚度及其导数—各向异性参数 $\delta$，这在定量地震解释中至关重要。