5. Conclusions
This study focuses on the use of Equilibrium Molecular Dynamics (EMD)
and Non-equilibrium MD (NEMD) simulations to investigate
hydrocarbon-water interactions, structure and transport in clay-hosted
nanopores with two different charged clay surface chemistries (H-H and
P-H nanopores). The following conclusions can be drawn from this work:
- Under a wide range of water concentration and pore sizes, P-H clay
pores support the formation of water bridges. In H-H pores, water is
largely present adjacent to the pore surface in an adsorbed layer.
There are limited instances where a water bridge forms in an H-H pore,
however.
- The strength of the self-generated electric field is stronger in P-H
pores in comparison to H-H pores for all pore widths. This promotes
the formation of a water bridge and strong alignment of the water
molecules with the electric field.
- With an imposed acceleration, the velocity profiles in H-H and P-H
clay pores are different. Water preferentially flows adjacent to the
pore surface for H-H pores with hydrocarbon occupying the center of
the pore. With P-H pores, the water bridge persists under acceleration
and a different velocity profile is observed irrespective of pore
width.
- As mentioned earlier, in H-H pores, water bridges can form under
specific conditions, but dissipate during flow. However, in P-H
nanopores, with the assistance of the electric field, water bridges
exist under flowing conditions.