First-principles calculation of the elastic moduli of sheet silicates and their application to shale anisotropy
First-principles calculation of the elastic moduli of sheet silicates and their application to shale anisotropy
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DOI：
10.2138/am.2011.3558
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发表时间：
2011
影响因子：
3.1
通讯作者：
B. Militzer;H. Wenk;Stephen Stackhouse;Lars Stixrude
中科院分区：
文献类型：
--
作者：
B. Militzer;H. Wenk;Stephen Stackhouse;Lars Stixrude
摘要 基于密度泛函理论，通过第一性原理计算推导了片状硅酸盐白云母、伊利石蒙皂石、高岭石、地开石和珍珠陶石的全弹性张量。对于白云母，计算特性与实验结果之间具有极好的一致性。研究发现阳离子紊乱的影响很小。另一方面，发现堆积无序与高岭土矿物有一定的相关性。还导出了每个相位相应的单晶地震波速度。这些表明高岭土矿物表现出一种独特类型的地震各向异性，我们将其与氢键联系起来。页岩骨料的弹性特性是通过计算贡献矿物相在其取向分布上的特性的平均值来预测的。计算出的弹性特性显示出更高的刚度和更低的 p 波各向异性。差异可能是由于天然样品中存在定向扁平孔，而在平均中没有考虑到这些孔。
Abstract The full elastic tensors of the sheet silicates muscovite, illite-smectite, kaolinite, dickite, and nacrite have been derived with first-principles calculations based on density functional theory. For muscovite, there is excellent agreement between calculated properties and experimental results. The influence of cation disorder was investigated and found to be minimal. On the other hand, stacking disorder is found to be of some relevance for kaolin minerals. The corresponding single-crystal seismic wave velocities were also derived for each phase. These revealed that kaolin minerals exhibit a distinct type of seismic anisotropy, which we relate to hydrogen bonding. The elastic properties of a shale aggregate was predicted by averaging the calculated properties of the contributing mineral phases over their orientation distributions. Calculated elastic properties display higher stiffness and lower p-wave anisotropy. The difference is likely due to the presence of oriented flattened pores in natural samples that are not taken into account in the averaging.