Molecular Dynamics Simulation Study of Carbon Dioxide - Hydrocarbon Mixtures Under Confinement
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Reducing carbon dioxide emissions in an attempt to control global warming is a critical issue being addressed at global level today. One method of regulating the amount of COv2 in the atmosphere is by re-injecting COv2 into reservoirs, thus in turn also improving the overall recovery of oil and gas. This is an enhanced oil/gas recovery technique which has received a lot of attention in industry. In this work, a study of the phenomena that allows for improved hydrocarbon recovery using COv2 injection into reservoir pores is presented. Additionally, an attempt to understand the effect of mixture density, concentration, temperature, moisture and the pore material on such systems will be discussed. Furthermore, the ways in which diffusivity of fluid behaves at the center of the pore as well as towards the pore walls is explored in detail in this work. All systems that have been simulated represent a canonical ensemble. Hence, at any given time, the number of molecules, the volume of the pore, and the temperature remain the same as specified at the beginning of a simulation. The work utilizes a methodology developed by Franco et al. to calculate the perpendicular self-diffusion co-efficient by obtaining the residence time from the integration of the survival probability. The methodology further allows for the calculation of the local self-diffusion coefficient in areas of interest as opposed to the global self-diffusion coefficient obtained from the commonly used Einstein relation. Results indicate that all studied characteristics of a system have a significant effect on the mobility and the configuration of the fluid within pore. Furthermore, these characteristics have a greater pronounced effect of the diffusivity at the center of the pore and a lesser effect in the region towards the wall. Further calculating the parallel self-diffusion coefficient of the fluid in the same systems analyzed in this work will provide even greater insight on the behavior of hydrocarbons within nanopores, in the presence of COv2.
Hamza, Muhammad (2019). Molecular Dynamics Simulation Study of Carbon Dioxide - Hydrocarbon Mixtures Under Confinement. Master's thesis, Texas A&M University. Available electronically from