(169d) An Atomistic Investigation of Hydrocarbon Behavior Confined in Kerogen Nanopores

The kerogen (a.k.a. a solvent insoluble organic matter in shales) holds a significant amount of hydrocarbons in free, adsorbed and absorbed forms. The limited understanding of hydrocarbon behavior confined in the nanoporous kerogen could be a limiting factor in the primary migration of hydrocarbons in kerogen and eventually on the overall hydrocarbon recovery in unconventional resources. A systematic investigation is performed to understand the influence of the chemical heterogeneity (of kerogen) and the variability in nanometer/subnanometer pore sizes (in kerogen) on the behavior of CH₄ confined in kerogen pores. In particular, the CH₄ distributed in free, adsorbed and absorbed forms are quantified based on the pore sizes. Monte Carlo/Molecular Dynamics simulation tools were used for the analysis. The proposed approach shed light on the complex hydrocarbon distribution in confined kerogen pore system, which is crucial to estimate the hydrocarbon in place and fraction of the hydrocarbon that are recoverable. Further, the proposed approach can be readily extended for long chain hydrocarbons and have broad implications in enhanced hydrocarbon recovery from unconventional resources.