LAUSR

Abstract CO 2 /H 2 O intercalation causes changes in the elastic mechanical properties of clay. This phenomenon is critical to geologic carbon sequestration (GCS) and enhancing oil rate (EOR) via CO 2 adsorption. In this work, the elastic stiffness and hydrostatic mechanical behavior of Na-montmorillonite (MMT) exposure to variable component of CO 2 /H 2 O mixture are investigated using combinations of Monte Carlo and Molecular Dynamic methods. In the hydrostatic test simulation of 1 W and 2 W hydrated state, volume and basal spacing d 001 linearly decrease with the increasing hydrostatic pressure. Moreover, gradients of 1 W hydrated state are smaller than that of the gradients of 2 W hydrated state. The linear gradient is related to the elastic modulus. Therefore higher hydrated state results in softer structure. Additionally, the yielding bulk modulus linearly decreases with the pressure. The decreasing gradient almost keeps at a constant of 1.0 GPa/GPa with variable component of CO 2 /H 2 O. At the super critical condition of CO 2 ( P  = 0.01 GPa, T  = 304.5 K), the elastic stiffness fluctuates with the variable component of H 2 O/CO 2 . CO 2 intercalation strongly affects the out-of-plane elastic stiffness while has little influence on the in-plane stiffness.