Supercritical CO2 may be an alternative to conventional fluids used in hydraulic fracturing which would avoid the introduction of potentially hazardous chemicals to the environment as well promoting CO2 sequestration. Density Functional Theory with the b3lyp/6-311++G(d,p) functional was used to model CH4, CO2, and their respective interactions with montmorillonite surfaces to determine surface complexes and adsorption energies. Ultimately, the difference in the ?Gads values will determine if carbon dioxide is able to desorb methane from the surfaces of the clay mineral layers. Models were developed with GaussView, energy minimized with Gaussian 09, and analyzed with Molden in order to get an array of data representing a variety of experimental conditions. Experimental isotherms for CH4 and CO2 are available in the literature, from which ?Gads values were calculated. These quantities were also calculated from the atomistic level computations. The synergy of experimental and theoretical data for adsorption processes will provide a molecular-level understanding of the interaction of the molecules with the substrate, contributing to the understanding of hydraulic fracturing processes.

Atomistic level computation of CH<sub>4</sub> and CO<sub>2</sub> interactions with clay mineral surfaces

247th National Meeting (2014)

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Atomistic level computation of CH4 and CO2 interactions with clay mineral surfaces

Atomistic level computation of CH₄ and CO₂ interactions with clay mineral surfaces