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 (HH and PH
nanopores). The following conclusions can be drawn from this work:
- Under different water concentrations and pore sizes, PH clay pores
support the formation of water bridges. In HH pore systems, water is
largely present adjacent to the pore surface in an adsorbed layer.
There are limited instances where a water bridge forms in an HH pore,
however.
- The strength of the self-generated electric field is stronger in PH
pores in comparison to HH pores for all pore widths. This favors the
water bridge phenomenon and strong alignment of the water molecules
with the electric field.
- With an imposed acceleration, the velocity profiles in HH and PH clay
pores are different. Water preferentially flows adjacent to the pore
surface for HH pores with hydrocarbon occupying the center of the
pore. With PH pores, the water bridge persists under acceleration and
a different velocity profile is observed irrespective of pore width.
- As mentioned earlier, in HH pores, water bridges can form under
specific conditions, but dissipate during flow. However, in PH
nanopores, with the assistance of the electric field, water bridges
exist under flowing conditions.