Insight into adsorption behaviors of shale oil in kerogen slit by molecular dynamics

Abstract

Shale oil is predominantly stored in organic nanopores, with kerogen playing a pivotal role in its adsorption. This study utilizes molecular dynamics (MD) simulations to quantitatively investigate the adsorption behavior of multi-component shale oil within kerogen slits. Unlike previous studies that focused on single-component hydrocarbon fluids and simplified kerogen models to graphene, this research employs an authentic kerogen structure and a multi-component shale oil model, incorporating the effects of surface roughness. The research analyzes the interaction mechanisms and distribution patterns of light, medium, and heavy components within the pores. Additionally, it examines the effects of temperature, pore size, and wall surface physical and chemical properties on shale oil adsorption. Results indicate that strong adsorption between asphaltene and kerogen significantly reduces the width of the kerogen slits, inhibiting the adsorption of lighter components. The study introduces the concept of effective radius for kerogen slits and provides a quantitative analysis of the adsorption capacity of kerogen surfaces. Different kerogen surface roughness and chemical properties were compared to understand their influence on shale oil adsorption. Key findings show that with increasing temperature, the distribution of hydrocarbons becomes more uniform, with medium components showing the most significant response. Surface roughness of kerogen affects the adsorption capacity, although the component proportions remain consistent, while different chemical property surfaces influence selective adsorption and the overall adsorption amount of shale oil components. This research offers a deeper understanding of shale oil adsorption mechanisms and provides valuable insights for optimizing shale oil extraction and utilization.