(505d) High-Pressure Adsorption of Gases On Albany Shales: Measurements and Modeling

Gas shales have become an important resource for natural gas. Further, they are potentially attractive sites for sequestering CO₂. Since a large proportion of gas in shale reservoirs are in an adsorbed state, knowledge of adsorption behavior on shales is required for design of optimal sequestration processes. However, there appear to be limited measurements in the literature for adsorption on shales. In this work, the adsorption isotherms of pure methane, nitrogen and CO₂ have been measured on Albany Shales. The as-received sample was used for these isotherm measurements. For each isotherm, the expected experimental uncertainties were estimated by propagating errors in the primary measurements.

The newly acquired adsorption data was modeled with the simplified local-density/Peng-Robinson (SLD-PR) adsorption model. The SLD model is a local form of the more general density functional theory and has been used successfully in our previous work to predict high-pressure, supercritical gas adsorption on a variety of coals and activated carbons. The SLD-PR model results obtained for the adsorption isotherms on shales indicate that the newly acquired adsorption data can be represented within the expected experimental uncertainties of the measurements. The model parameterization used appears to be effective in obtaining precise model representations for the systems considered.