Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
〈MSE〉2, UMI 3466 CNRS-MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
Nat Mater. 2016 May;15(5):576-82. doi: 10.1038/nmat4541. Epub 2016 Feb 1.
Despite kerogen's importance as the organic backbone for hydrocarbon production from source rocks such as gas shale, the interplay between kerogen's chemistry, morphology and mechanics remains unexplored. As the environmental impact of shale gas rises, identifying functional relations between its geochemical, transport, elastic and fracture properties from realistic molecular models of kerogens becomes all the more important. Here, by using a hybrid experimental-simulation method, we propose a panel of realistic molecular models of mature and immature kerogens that provide a detailed picture of kerogen's nanostructure without considering the presence of clays and other minerals in shales. We probe the models' strengths and limitations, and show that they predict essential features amenable to experimental validation, including pore distribution, vibrational density of states and stiffness. We also show that kerogen's maturation, which manifests itself as an increase in the sp(2)/sp(3) hybridization ratio, entails a crossover from plastic-to-brittle rupture mechanisms.
尽管干酪根作为烃类生产的有机骨架对于天然气页岩等源岩非常重要，但干酪根的化学、形态和力学之间的相互作用仍未得到探索。随着页岩气的环境影响不断增加，从干酪根的现实分子模型中识别其地球化学、输运、弹性和断裂特性之间的功能关系变得尤为重要。在这里，我们通过使用混合实验-模拟方法，提出了一系列成熟和不成熟干酪根的现实分子模型，这些模型提供了干酪根纳米结构的详细图片，而不考虑页岩中粘土和其他矿物质的存在。我们探究了这些模型的优缺点，并表明它们可以预测一些基本特征，这些特征可以通过实验验证，包括孔隙分布、振动态密度和刚度。我们还表明，干酪根的成熟化，表现为 sp(2)/sp(3) 杂化比的增加，导致从塑性到脆性断裂机制的转变。
