MOLECULAR MODELING OF MULTICOMPONENT ADSORPTION ON HETEROGENEOUS SHALE MINERALS

An accurate description of the adsorption behavior of components such as CO2 and CH4 as well as surfactants, on shale is of importance in understanding the storage mechanism and production of gases in shale formations. Molecular simulation enjoys a high preference for use in shale gas adsorption studies. However, modeling and preparing a realistic shale topology remains a constraint. The majority of studies are performed using a single component, such as kerogen or montmorillonite, to represent shale surface. Where more than one component is used, they are not mixed but are at different ends of the nanopores. These surfaces do not bear similitude to actual shale surfaces in terms of heterogeneity and multiplicity of minerals. Moreover, disparities have been observed between simulation and experimental results. In this work, an heterogenous molecular shale model prepared from montmorillonite, type IID kerogen, quartz, and illite clay minerals was developed using molecular dynamics and simulation. Properties of the model were matched to properties of actual shale as obtained from characterization experiments and literature. The results from the adsorption simulation studies on the shale model show that the model matches experimental adsorption values than the single mineral models. Multicomponent adsorption using molecular dynamics and simulation was also performed on this model to garner insights into the adsorption behavior of different components.