3. Distribution of Water and Hydrocarbon in P-H and H-H
Nanopores
Fig. 4 shows the equilibrium
configurations and number density profiles (along z-direction) for water
and hydrocarbon in 5 nm H-H (Fig.4a-b) and P-H (Fig. 4c-d) nanopores. We
do not show the illite structure for clarity.
Fig. 4a shows a water film adjacent to the clay surfaces in the H-H pore
system. Water preferentially adsorbs because of the strong electrostatic
interaction between water and the surfaces82 and the
formation of a hydrogen bond between water and the surface hydroxyl and
oxygen groups83. This observation is analogous to
water adsorption in silica-based pore structures76,84.
Increasing the water concentration to 58.82% as shown in Fig.4b leads
to an increase in the adsorbed film thickness. The number density of
water (shown in the blue line) and hydrocarbon (black solid line) are
relatively constant across the pore.