Molecular dynamics simulations are carried out to study formation and stability of nanometer thick films of heptane in water. The system is considered as a representative model of oil films in aqueous media encountered during deemulsification of water droplets in diluted oil. The simulations are performed using the Gromacs freeware employing the Gromos96 force field. The simulations are conducted assuming simple point charge (SPC) model of water in different simulation box sizes. Dependence of the system potential energy on the thickness of heptane layer is obtained from these simulations. It is established that our molecular dynamics simulations are independent of the size of the simulation box. The effective Hamaker constant of heptane-water systems calculated from our simulations is in excellent agreement with its experimentally reported value. Molecular dynamics simulations allow determination of the diffusion coefficients of heptane and water, which are directly compared with experimental data. A good agreement is found between the simulated heptane self-diffusivity and its literature reported value. The curvature of the heptane/water interface along with the heptane volume fraction were found to cause rupture of the heptane layer resulting in the formation of cylindrical-shape micelles. The simulations are capable of providing the disjoining pressure isotherms of heptane films in water. It was observed that although the continuum models are sufficiently accurate for such films as long the film thickness is above 3 nm, these models are generally inadequate for thinner films. In such thin films (thickness 1 nm), the heptane layer tends to become "permeable" and water molecules tend to diffuse across the heptane layer causing a rupture of the film.