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:
  1. 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.
  2. 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.
  3. 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.
  4. 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.