Molecular dynamics simulation of methane gas flow in nanopores

Abstract

The transport properties of fluids in nanopores are a fundamental scientific issue in the development of tight reservoirs such as shale gas. The flow of gas in nanosized pores is affected by a size effect, therefore, the conventional fluid mechanics theory cannot be applied. Based on the molecular dynamics theory, the transport process of methane in carbon nanopores was studied, including simulation of the arrangement of the wall atoms, slip and transitional flow of methane in the supercritical state and application of different driving forces. The research of this paper revealed that the configuration of the wall carbon atoms, at the microscale, has a greater influence on the density distribution and velocity distribution of methane molecules in the pores, while the change in the driving force has a greater impact on the slippage of methane at the boundary. Particularly, the theoretical model we proposed can predict the transport properties in carbon nanopores, demonstrating the sensitivity of driving force, pore configuration and the state of flow for methane gas transport, which can provide the characteristic parameters for the establishment of the seepage mathematical model. Keywords: Molecular dynamics, Shale gas, Transport property, Carbon nanopore, Numerical simulation