Fine-grained sediments and sedimentary rocks play important roles in a variety of modern energy technologies, from petroleum geology to geological carbon sequestration and radioactive waste management. Yet, despite their utility and ubiquity, many of their properties remain poorly understood. In particular, the ability to predict the permeability and mechanics of these media remains a persistent fundamental challenges in the geosciences with potentially transformative implications. In the present work, we show how large-scale classical molecular dynamics (MD) simulations can be used to help interpret the properties of fine-grained sedimentary material. All-atom simulations containing multiple discrete clay particles are utilized to understand the evolution of a clay nanoparticle suspension during its progressive dehydration. Microstructural properties (pore size distribution, tortuosity, anisotropy), mechanical properties (swelling pressure), thermodynamic properties (enthalpy and free energy of hydration, anion exclusion), and transport properties (diffusion coefficients of water and sodium, and hydraulic permeability) are all calculated and compared to experiment. Overall, our results shed light into the important role of water films in controlling the coupled chemistry, mechanics, and hydrology of clayey soils, engineered clay barriers, and argillaceous sedimentary media.

Molecular dynamics simulation of a clay nanoparticle suspension during dehydration

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.