CHANGES IN THE INTERLAYER STRUCTURE AND THERMODYNAMICS OF HYDRATED MONTMORILLONITE UNDER BASIN CONDITIONS: MOLECULAR SIMULATION APPROACHES

摘要: Interlayer swelling of hydrated montmorillonite is an important issue in clay mineralogy. Although the behavior under ambient conditions has been investigated comprehensively, effects basin on hydration and behaviors have not characterized thoroughly. In present study, molecular dynamics simulations were employed to reveal changes interlayer structure Na-montmorillonite high temperatures pressures conditions. According calculation immersion energy, monolayer hydrate becomes more stable than bilayer at a burial depth 7 km (at temperature 518 K lithostatic pressure 1.04 kbar). With increasing depth, basal spacings hydrates change varying degrees. The density-distribution profiles species exhibit variation structures due change, especially hydrate. Na+ ions prefer distribute closer layers. mobility water increases with temperature, while caused these decrease.