(563g) In-situ multi-scale characterization of the adsorption and desorption behaviors of CO2 with shale for sustainable extraction of unconventional hydrocarbons

Increasing demand for energy in the global economy has a detrimental impact on the overall sustainability of the planet. In the United States, shale gas and oil have emerged as significant energy resources. Current approaches to use water for hydrofracking are environmentally unsustainable in the long run and alternative fracturing fluids such as CO₂ need to be explored for sustainable energy extraction. The key factors to evaluate are the changes in the pore volume and the chemical compositions of shales when reacted with CO₂. Particularly, the in-situ adsorption and desorption behavior of CO₂ on shales and the corresponding chemical and structural changes in shales are important to investigate for the sustainable extraction of unconventional hydrocarbons. In this study, simultaneous in-situ measurements of the changes in the molecular structure, microstructure, and pore volume of shales during adsorption and desorption of CO₂ are performed using Wide, Small, and Ultra-Small Angle X-Ray Scattering (WAXS/SAXS/USAXS) to determine whether the chemical and structural changes are reversible or irreversible. In addition, the effects of CO₂ on the chemical and morphological changes of shales in the presence and absence of variable amounts of water at elevated temperatures and pressures (T_max = 80^oC, P_max = 150 atm) showed that increasing the water content increases the pore spaces in shales by inducing chemical changes.