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