Mechanism of oil molecules transportation in nano-sized shale channel: MD simulation

Abstract

Unconventional energy, such as shale oil and gas, opens up a new avenue for alleviating the pressure on the use of conventional energy, enabling a sustainable development of economy and industry. We firstly explored the mechanism of oil molecules transportation in a nano-sized shale channel by molecular dynamic simulations. It is demonstrated that the competition between the oil adsorption strength to the shale surface and the driving force from gas flooding (N₂) plays the dominant role in the oil translocation process in the shale channel. The encapsulated oil molecules would be expelled by gas flooding when the gas pressure reaches a critical value. Besides, it is found that the pressure of the gas flooding, shale channel pore size, N₂ amount, temperature and shale component all have an important effect on the translocation process of oil molecules inside the shale channel, whose oil-driving efficiency is characterized by oil displacement distance and oil displacement loss. This work lays a theoretical foundation to achieve effectively and efficiently exploiting oil. Besides, the result may shed light on explaining many industrial processes and natural phenomena in nano-sized channels, including viscous liquid transport or diffusion through membranes, energy conversion devices, biological molecules (hemoglobin, protein, DNA) translocation and so forth.